ATI has problems running it's own games on it's own video cards.
Just for clarity, there is no such thing as an ATI or nVidia game, both companies make hardware and forceware for said hardware, and do not design games. This statement might be true if you were to say ATI cards excel in DX9.0, and nVidia cards excel in OpenGL, but nVidia performs better overall better in both.
Shibby, you should be all right with the x800XL if you're a bit tight for cash as it's the cheapest and best value 16 pipeline card you'll find, but if you have the money, I'd recommend a 6800GT simply for added PS3.0 instructions.
As far as G.Skill goes, I am assuming you live in Canada. I will tell you now you will not be able to find G.Skill LA RAM anywhere in Canada (and even if you could I'm sure it'd cost $400+). Any Samsung TCCD based RAM is just as good as G.Skill. OCZ Plantium Revision 3 PC3200 RAM uses TCCD, and should perform right on par with the G.SKill. I know it's fairly abudant in Canada and if you are having trouble finding any PM me and I'll point you in the right direction.
the ocz ram with pc4000 is just overclocked 3200
Again, just to clarify, it isn't overclocked as it's built and tested to run at stock speeds, stock timings and stock voltages perfectly stable. I would recommend the Rev2s over this stuff though as I'm certain you'll get farther with 'em.
And the 3200+ you're looking at, I recommend you buy the 3200+ with the Venice core rather than the Winchester core. I know they have the Venice 3200+ availible at ncix.com (I just ordered one a few days ago actually). The Venice uses the same 90nm process as the Winny, but it has added SSE3 instruction support and better overall architechture. I've seen 3200+ venices hitting 3.0GHz on air.