Swathi,
I think first
you should decide whether you want to take dba or developer certifications. developer certifications tests your
knowledge in forms,reports etc. and dba certification is for experienced / aspiring dba's. Oracle recommends one to have
atleast a few years of exp as a dba before going for certification..well, its up to you..
If you want to get certified as a dba(which is what i am doing) , you can get certified in 8i/9i/10g.
But,I would suggest you take atleast 8i or 9i first, so that you will also have some knowledge of previous versions of oracle
and 8i/9i is still a valuable credential to have.
If you want to save some money, you can take 8i first and then upgrade to 9i/10g because the ILT requirement is not there for
8i.
Thanks
Chitts