Maximum PC

I'll put it strait. I have a very basic idea about upgrading with the biggest thing I've done is add more RAM.

I would like it very much if I could add to the power of my desktop as it only has 220W.
I would ideally like to add some more power so I could improve my graphics card and other things.
My computer is an Aspire AX 3900 (the case is pretty thin and small which is a problem).
It has: Intel i5 @3.20 processor
6GB RAM
Raedon 4650 1GB Graphics
1TB Hard Drive Space
Windows 7 Home Premium
64 Bit Operating System

Hopefully someone show me a good PSU to have. I really do not want to get a new case and I know that will probably restrict my options.
I do not know if I have given enough information about my computer and if not could someone please tell me what to add.

If anybody could help me to improve my graphics card at the same that would be really great. (Maybe to 2GB if possible)

I'm sorry to waste your time but I have looked for help at other places but couldn't find anything and I'm not the most knowledgeable about computer hardware.

is it a standard ATX power supply or one of those pos nonstandard PS that some manufactures like to use?

Never mind a quick google surch provided it was proprietary.

Here is a post all about what your trying to do:
http://answers.yahoo.com/question/index?qid=20120325012358AAT207Q