To Install an new exchange on a domain that already has AD
installed:
1. Make sure all the following are installd and working o
the server SMTP, NNTP, ASP.NET, IIS, WWW. This can be
installed windos component on Add-Remove program
2. Run Forest Preain Prep
3. Run Domain Prep and you are good to go.

well, this is not a good pratice to so and the reasons
behind are :

1. Redundancy and Stability - if the exchange server fails
then Domain Controller also fails and it concludes a big
failure...

2. Overload : It may overload your existing server and that
can cause a significant performance problem.

well if think there is something important that i missed
please inform me via mail.

well, this is not a good pratice to so and the reasons
behind are :

1. Redundancy and Stability 
2. Overload

Besides stability, redundancy and overload. The major reason
is that both Exchange and DC use port 389 for LDAP queries.
If you install both on same machine it results in port
conflicts. 

For more info search for "LDAP and Exchange port conflict"

REFERENCE TO ANSWER 3. 
 
The condition applies to exchange 5.x version only , here is
the reference :

http://support.microsoft.com/kb/q224447



I am not sure about which ports does exchange 2k and 2k3
uses ..If anybody can tell, plz put it here ..

I found :

http://www.petri.co.il/ports_used_by_exchange.htm

But even this link does not say that port 389 is used by
exchange 2k/2k3 servers

Exchange 5.5 does not integrate with the NT4 domain or the 
Windows 2000/2003 Active Directory in a meaningful way. A 
single user could be associated with several different 
mailboxes. Exchange 2000/2003/2007 integrates tightly with 
Active Directory, and there is a 1:1 relationship between 
mailboxes and AD user accounts. 
There are other differences, depending on whether you have 
a standard or enterprise version as it relates to maximum 
database size, but the directory integration is probably 
the biggest difference.

1.Standard 
2.Enterprise

You may have used Link Image at design time (while 
inseerting OLE object) therefore report requires it on 
machine on whihc report will be run. One can solve this 
problem by embeding image in report rather than linking it 
(by unchecking Link opetion while selecting image).

try { 
        // here i have define a simple datatable inwhich 
image will recide 
        DataTable dt = new DataTable(); 
        // object of data row 
        DataRow drow; 
        // add the column in table to store the image of 
Byte array type 
        dt.Columns.Add("Image", System.Type.GetType
("System.Byte[]")); 
        drow = dt.NewRow; 
        // define the filestream object to read the image 
        FileStream fs; 
        // define te binary reader to read the bytes of 
image 
        BinaryReader br; 
        // check the existance of image 
        if (File.Exists
(AppDomain.CurrentDomain.BaseDirectory + "10157.Jpg")) { 
            // open image in file stream 
            fs = new FileStream
(AppDomain.CurrentDomain.BaseDirectory + "10157.Jpg", 
FileMode.Open); 
        } 
        else { 
            // if phot does not exist show the nophoto.jpg 
file 
            fs = new FileStream
(AppDomain.CurrentDomain.BaseDirectory + "NoPhoto.jpg", 
FileMode.Open); 
        } 
        // initialise the binary reader from file 
streamobject 
        br = new BinaryReader(fs); 
        // define the byte array of filelength 
        byte[] imgbyte = new byte[fs.Length + 1]; 
        // read the bytes from the binary reader 
        imgbyte = br.ReadBytes(Convert.ToInt32
((fs.Length))); 
        drow(0) = imgbyte; 
        // add the image in bytearray 
        dt.Rows.Add(drow); 
        // add row into the datatable 
        br.Close(); 
        // close the binary reader 
        fs.Close(); 
        // close the file stream 
        CrystalReport1 rptobj = new CrystalReport1(); 
        // object of crystal report 
        rptobj.SetDataSource(dt); 
        // set the datasource of crystalreport object 
        CrystalReportViewer1.ReportSource = rptobj; 
        //set the report source 
    } 
    catch (Exception ex) { 
        // error handling 
        Interaction.MsgBox("Missing 10157.jpg or 
nophoto.jpg in application folder"); 
    }

Arraylist itself is a part of collection. 
From a .NET perspective, a collection could be defined as 
an object that implements one or more of the 
System.Collections.ICollection, 
System.Collections.IDictionary, and 
System.Collections.IList interfaces.
 
This definition leads to my classification of the "built-
in" collections found in the System.Collections namespace 
into three broad categories:
Ordered collections: Collections that implement only the 
ICollection interface are usually distinguished by the fact 
that insertion order controls the order in which objects 
may be retrieved from the collection. The 
System.Collections.Stack and System.Collections.Queue 
classes are both examples of ICollection collections.
Indexed collections: IList-implementing collections are 
distinguished by the fact that their contents can be 
retrieved via a zero-based numeric index, like an array. 
The System.Collections.ArrayList object is one example of 
an indexed collection.
Keyed collections: Collections implementing the IDictionary 
interface contain items that can be retrieved by an 
associated key value of some kind. The contents of 
IDictionary collections are also usually sorted in some 
fashion based on the key valu and can be retrieved in 
sorted order by enumeration. The 
System.Collections.HashTable class implements the 
IDictionary interface.

ArrayList
 
The System.Collections.ArrayList class, which implements 
only IList, could best be described as a hybrid of a normal 
array and a collection. ArrayLists hold items in the order 
they were added. Items are assigned an index identifier and 
can be retrieved in any order via their associated index 
number. The ArrayList grows as new items are added to it, 
which makes it more flexible than a normal array. However, 
an ArrayList has more overhead than a traditional array and 
is not strongly typed, accepting anything that can be cast 
to System.Object (in other words, everything).

l

configuration setting is applied to specific file/folder 
with appropriate "Path" attribute.
e.g
1)applying setting to everything under System.web
<location path="Administrator" > 
 <system.web>
    <authorization> 
          <deny users="?" />
          <allow roles="Administrator" /> 
          <deny users="*" />
    </authorization>
 </system.web> 
</location>

2)applying setting to specific directory called "folder1"

<!— Configuration for the "folder1" subdirectory. -->
   <location path="sub1">
      <system.web>
         <httpHandlers>
            <add verb="*" path="folder1.Scott" 
type="folder1.Scott"/>
            <add verb="*" path="folder1.David" 
type="folder1.David"/>
         </httpHandlers>
      </system.web>
   </location>

constructor are called in this order
a,b,c

When you intantiate Class C then the Class C Constructor 
calls its base class(class b) constructor, Class b calls 
its baseclass constructor i.e Class a, Class a calls its 
base class constructor System.object.System.object 
intiallizes class fields, then it comes to Class a it 
intializes thier class fields and it comes to Class b after 
intilalizion at last the Class C constructor intializes 
their class fields.
Hence the Hierarchy of class Constructors are called are 
a , b, c