New AMD 955 or i7 build now or wait for windows 7?

Currently I have a fairly old system. It’s an HP a1130n.

System Specs:
300 watt power supply (can’t really get a new graphics card with this)
Amd fx-55 (MoBo can’t handle anything higher)
Ati radeon x800xl (256mb graphics card)
2gb of ram, running windows xp


So my questions are,
1)Should I try and wait for windows 7? Most likely I would upgrade to it from vista
2) Would a 4870 be good for a while with the DX11 cards coming out soon?
3) Should I wait for summer for some possible deals?

And here would be my new system,
-Either an AMD 955 BE or Intel i7 920 (what do you think for gaming? I’m leaning more towards AMD though)
-Ati 4870
- 4 or 8gb of RAM, probably 8 with windows 7
-mobo im not to biased toward any company

Thx in advance, this is my first post here so sorry if I put this in wrong section
Thx,
Mugz

I use my computer more for gaming, and i don't really want to spend over 1200 ( i can actually get a decent i7 build for that) but AMD is a little cheaper and seems to be just as good for gaming. I don't need to encode anything to fast because that wouldn't be its primary use. Also, would this be a decent upgrade that would last for about 3 years? after summer i would still like to spend the same amount but my computer is getting pretty slow now and rather get something sooner.

I did notice the *How To Ask For New Build Advice*.... unfortunately it was after I posted