Budget Build

[Gasparovachi]

I have around 800 bucks to work with, but I will get more money later so I want to keep it compatible with higher performance parts but at a lower price. I want a gaming computer so I pretty much just took off an expensive GPU from the build, so it costs a lot less.
I have a lot of older games from around 05-06 (BF2, HL2, that kind of thing) so I won't be getting vista yet, I'm keeping my XP until the GPU upgrade. So my question is, can you make this build cost less and still be as effective or better? And will it run games like Battlefield 2 and Half Life 2 on high settings with a stable FPS around 30 or more? Is it upgradeable to crysis standards? (or atleast newer games)

CPU (Q6600)
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115017
Cooler (Arctic Cooling Freezer)
http://www.newegg.com/Product/Product.aspx?Item=N82E16835186134
How high will I be able to overclock the CPU with this cooler?

MoBo (Gigabyte)
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128359

RAM (OCZ 4 GB)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227298
I only have 32-bit windows XP, so will this be fine until I can get 64-bit vista? How much RAM will be utilized by 32-bit?

GPU (9400 GT)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814143153
I just need to run BF2 and HL2 in high with no lag, is this too much? Can I get something cheaper?

PSU (Corsair 730W)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139006
Will 730W be enough to power up to a HD4870 or a GTX 260/280?

HDD (WD 500GB 7200 RPM SATA 3.0 GB/s)
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136320

Case (COOLER MASTER)
http://www.newegg.com/Product/Product.aspx?Item=N82E16811119077
I am gonna screw in and extra 80mm fan on the window if I can, if I can't I'll put it near the top

So yeah, that is pretty much it, thanks for the help if you contribute!

 

[Dystopia]

Seems a good build. But I would get the 3850 or the 4670 Over the 9400GT. Even the 8600GTS might be better, because I think like the way things are with the 9XXX and 8XXX series is that if you have say, the 9400GT, it is around as good, somewaht better than the 8500GT. The 8600GTS would be better and is cheaper.