Migrating to a new Oracle version

Problem:
I'm a Java programmer and a Transact SQL DBA. So i have knowledge about databases but now we have a database who performs very bad and got much deadlock problems and so on. It's an Oracle Database.

We have Oracle version 9 and an application in Delphi. The bad performance is only since a while. We have cleaned the archive.
My suggestion is why not migrate to a newer version of Oracle. Change some hardware specs get up to date.Then i think we will have less problems.

But ofcourse this is more trail on erro. That why i hope there is an Oracle specialist here who can help me with a few questions.

Users and Specs
I got 150 till 180 users
i got a server with one processor XEON 233 GHZ
4 gig memory

Questions
1. Is it an idea to upgrade? Maybe not to solve al the problems, but version 9 is old, there is version 10 or 11.

2. Which version we should use 10 or 11. 11 is in use for a while so this sounds like a good idea.

3. Are the specs OK or must i do something about the server to?
Maybe dual core, or Enterprise (64 bit)

4. Maybe for 64 bit i need Oracle version 11 to have good support on it?

I hope somebody can help me a bit.

Thanks,

Kind regards,

André

You don't think that, possibly, the Oracle forums at OTN would be a better place to ask an Oracle migration question like this? They being run by Oracle and all.

Thanks for your reply. I have a userid for the Oracle site, so the forum works for me.
I will try it there.