Swapna... U don't need to go to depth. Just basics will be
enough. Since u r from computer background, questions
related to banking will be less. But general questions will
be asked.

GM of sbi
Number of branches
First bank in India
Largest bank in the world
Some questions related to recession.
Recent happenings in banking industry.
Country using plastic currency.

These are some questions I collected from previous candidates.

LAN
internet
E-Governance
E-commerce
Internet banking
ATM - Protocol used (people use automatic instead of
AUTOMATED. It's wrong) 
difference between internet banking and ATM


If the interviewer is good enough in computer knowledge, u
can expect him to ask difficult questions. We can answer
these questions generally and technically. If the
interviewer looks unsatisfied, try more technical answer.

Diff btwn c and c++
E-commerce applications etc.

They can ask some funny questions or very easy common sense
questions to reduce the pressure. 

Post your experience after the interview. All the very best.

Hey... I'm not an expert. My aunt is working in SBT. She
gave me these guidelines. I'm about to attend the interview
on 27-5-2009. In Ernakulam (kerala). :-)