I am building my first rig as a mid range gaming pc.
Parts:
Case: Sunbeam Silent Storm IC-SS-SVBK Black/Silver $49.99
http://www.newegg.com/Product/Prod [...] 6811166030
Includes 3 120mm fans(side,back,core) but will be getting one for front and possibly seconds for sides/back.

Power Supply: Antec TPQ-850 850W $139.99
http://www.newegg.com/Product/Prod [...] 6817371009

Video Card: ZOTAC ZT-88SES2P-FSP GeForce 8800GTS (G92) 512MB(found it for $120)
http://www.newegg.com/Product/Prod [...] 6814500004

CPU: Intel Core 2 Quad Q6600 Kentsfield 2.4GHz $199.99
http://www.newegg.com/Product/Prod [...] 6819115017

CPU cooler: ARCTIC COOLING Freezer 7 Pro $26.99
http://www.newegg.com/Product/Prod [...] 6835186134

Motherboard: ASUS P5N32-E SLI LGA 775 NVIDIA nForce 680i $142.50
http://www.newegg.com/Product/Prod [...] 813131073R

Memory: Patriot Extreme Performance 2GB 33.99
http://www.newegg.com/Product/Prod [...] 6820220144
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I already have a monitor, hard drive, keyboard, mouse, wireless card etc.
The main thing I am not sure about is the motherboard because I don't know if SLI will ever be necessary for me. The new monitor I am getting eventually will be no bigger than lower range of 20 inches.
Let me know what you think and if you think there are better parts/better bang for buck. Any help is greatly appreciated.

I honestly think you can get a better bang for your buck by going with a P35 or P45 and get a 4850 or 4870.

I have a 780i (and had a 680i) and like them, and currently have the 8800 gts, but if I was buying today, I would go for an intel board and an ati card.

Nice, but i would take a Intel E8400 or E8500. They are faster and no games need an Quad core it's an Overkill. Memory, you need to take 4GB because the most games need now 2GB in a year the most games need 4Gb, so take a 4GB. Do you have a CPU cooler ? because if you want to overclock your pc you need an CPU cooler.

Greets
Ruben

ok i will just make my suggestions in order of the way you listed the parts also a budget would help

case: this is really just opinion get what you like but you may want to try the antec 300

PSU: 850watt is probably more than you need i would check out the corsair 750watt it has better efficiency

GPU: the 4850 is a little more but well worth it

CPU: the Q6600 is great the 8400 is good to but the Q6600 is where i would go just because more and more games like UT3 and crysis will start to use it and if you want this build to last just that much longer it will really help

CPU cooler: just fine

motherboard: if you go with the 4850 which i recommend you do then the P45 is a good board if you don't want to do crossfire if you think you are going to want to do go with a x38 or x48 board

RAM: 4GB is good to go with but make sure you have a 64bit OS

How much better is 4850 than the 8800GTS?

Well it benched better than the 8800Ultra for Crysis at Toms hardware review.

Would say be worth selling a $120 8800GTS at equal price or slight loss to get an ati 4850 or 4870?

Don't worry about getting a 4850 if you don't want to spend more money, unless you have a fetish for great fps on highest settings on every game. But for great future proofing/longer lasting bang for the buck get a 150 dollar p45 crossfire mobo and buy a 4850 instead, then later uprade to another 4850 in crossfire.

The video card was just purchases 1 and half weeks ago from FXvideocards as gift from friend. Still has completely original packaging except for little square cut out of video card box that contained codes. Should I try for refund or just sell on eBay to get money back because I think the 4850 is worth it. I wouldn't call it a fetish but who doesn't love killer fps?

With a decent overclock, the 8800GTS will basically be the same as a 9800GTX, which trades blows or performs slightly worse than the 4850. So it's not really a blowout, I don't think, though it seems like the 4850 stands to improve more from driver updates and the like.

A P35 or P45 board is probably a good choice. And if you're not sure you'd go with a dual graphics solution, abandon the solution altogether... by the time you'd get around to adding another card, it'd likely be better to just buy a newer, better single card than to add a second card to the system.

A 500ish W PSU ought to handle this system just fine, something like Corsair's 550VX. Oh, and 4GB of memory is cheap - you might as well get some more! Get a 2x2GB kit of DDR2-800 with tight timings and low voltages (the best combo of those two things, preferably), or just some cheap stuff