This is likely a 24/7 machine for everyday use, gaming, video encoding, various other tasks, etc.  I plan to OC this quite a bit, and I want cool temps, a stable system, and so on.  Noise isn't that much of an issue.  I don't plan on upgrading this for awhile: 8GB of RAM when it becomes necessary, but not much beyond that.  I haven't even glanced at hardware in the past 4 years so I'm pretty new at this.

CPU: Intel Core 2 Quad Q9450
http://www.newegg.com/Product/Product.aspx?item=N82E16819115042

MOBO: Abit IP35 Pro
http://www.newegg.com/Product/Product.aspx?item=N82E16813127030

RAM: Corsair Dominator 4GB DDR2 1066Mhz
http://www.newegg.com/Product/Product.aspx?item=N82E16820145197

GPU: EVGA 8800 GTS 512MB (G92)
http://www.newegg.com/Product/Product.aspx?item=N82E16814130325

CASE: Antec Twelve Hundred
http://www.newegg.com/Product/Product.aspx?item=N82E16811129043

HD: Seagate Barracuda ES.2 750GB
http://www.newegg.com/Product/Product.aspx?item=N82E16822148295

OPTICAL: Lite-On 20X DVD-RW w/ LightScribe
http://www.newegg.com/Product/Product.aspx?item=N82E16827106072

PSU: Undecided.  Leaning towards OCZ GameXStream 700W (+12Vx4 = 18A), but maybe Thermaltake Purepower 500W is sufficient (+12Vx2 = 14A / 15A).
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341002
http://www.newegg.com/Product/Product.aspx?Item=N82E16817153052

CPU HSF: Undecided.  Leaning towards Sunbeam Core Contact if I can find it.  If not, Xigmatek HDT-S1283.
http://www.newegg.com/Product/Product.aspx?Item=N82E16835233003

GPU HSF: Undecided.  Given that this is dual slot, should I just go with stock, or do I pick up a Zalman VF1000?
http://www.newegg.com/Product/Product.aspx?Item=N82E16835118037
http://www.newegg.com/Product/Product.aspx?Item=N82E16835118038

TIM: OCZ Freeze
http://www.newegg.com/Product/Product.aspx?Item=N82E16835202006

OS: 32-bit XP, to eventually be replaced by 64-bit Vista, dual boot with Linux

I have no special plans to cool the HD/RAM/NB/SB, but I probably will add a case fan on the side panel.  Let me know if this looks good, or if there's anything else I should consider before going ahead.  My plan is to run Prime95 for 24 hours once I have everything set up.

 I'm not sure how dependable that thermal paste is. I reccomend Ceramique.

The default cooling for the 8800GTS is usually excellent.  I don't think you need additional cooling on it. 

 With windows 32 bit, it only recognizes 2.75GB of the ram. You can go check in the reviews.

It's still a boost over 2gb plus he'll be going 64-bit eventually, so no problems.  It's definitely a computer ready for the future, although I do think 4GB of RAM will be enough for a good while.  2GB is virtually always enough right now.