IN Windows 98,Right click on Network Neighbourhood and go 
to porperty and select TCP/IP then go to property of it and 
change the ip address.

In Windows 2000 there is a same process

IN Windows 98,Right click on Network Neighbourhood and go 
to porperty and select TCP/IP then go to property of it and 
change the ip address.

In Windows 2000 there is a same process


but 

 in command prompt netsh command

In Windows 95,98 select network neighbourhood right click 
Select properties select TCP Select proberties and Give the 
IP Address

In Windows 2000 Select My Network Places right click select 
properties select LAN card right click select properties 
select internet protocol/Transmission control Protocol 
select properties and give the IP