jdbc driver and 64 bit oracle

Hello ,
Today - we tried to migrate our application from a 32 bit Oracle 8i environment
to a 64bit Oracle 9i environment .

Whiel going through the application - we encountered a strange problem
where we invoke a stored procedure - and the stored procedure is supposed to return us a cursor handle which we use to loop through data in java .

What is observed is that on executing the stored procedure through java ( old jdbc driver that was supporting 8i ) the results were kind of screwed up

Executing the stored procedure stand alone from a prompt works fine .
The same code and driver when pointing to 8i 32 bit environment
gave us correct results

I am not good at this - but wanted to know - would the driver play a part ?
Would the driver need to be able to support the 64 bit environment ?
Is there a limitation to the way SQL is built in 91 as compared to 8i which could be causing this problem ?

( we are using a driver which is in a jar file - classes12.jar )

Thanks in advance ,
-anagha