$1,700 for gaming build

Okay 8GB is only needed if you multi-task or use programs such as photoshop, autocad, etc. If you only game and browse the web - you don't need 8GB of ram. Also will you plan to overclock, it would awesome if you fill in the sticky on this forum.

GPU - Sapphire ATI Radeon 4890 OC Edition
http://www.newegg.com/Product/Prod [...] 6814102831
$260 ($20 MIR, wait for the 1GHz edition if possible)

CPU - Intel i7 920
http://www.newegg.com/Product/Prod [...] 6819115202
$288

MB - Asus P6T x58
http://www.newegg.com/Product/Prod [...] 6813131359
$250

RAM - OCZ Platinum 6GB (3 x 2GB) DDR3 1600
http://www.newegg.com/Product/Prod [...] 6820227381
$95 ($20 MIR)

Case - Antec 1200 Full Tower ATX
http://www.newegg.com/Product/Prod [...] 811129043&
$160

Cooler - Noctua NH-U12P SE1366
http://www.newegg.com/Product/Prod [...] 6835608007
$80

Compound - Artic Silver 5
http://www.newegg.com/Product/Prod [...] 6835100007
$9

PSU (too much, but room for upgrades) - Antec 1000W
http://www.newegg.com/Product/Prod [...] 6817371012
$200 (Only get this you plan on getting the combo I listed below which comes with the Antec 1200)

OS
Windows Vista Home Preium
http://www.newegg.com/Product/Prod [...] 6832116488
$100

I don't know much about speakers.

Total: $1442 (Not including combos or MIR) (Including OS)

Combo Deals (Here you can find combo deals to save a good amount of cash)

GPU + CPU
http://www.newegg.com/Product/Comb [...] mbo.186989
Save $30

PSU + Case
http://www.newegg.com/Product/Comb [...] mbo.193731
Only get this combo is you want the 1000W PSU
Save $40

Hard Drive + OS
http://www.newegg.com/Product/Comb [...] mbo.186062
1Tb WD 7.2k Hard Drive
Save $20

With combos: $1352 (Including OS)
With MIRS + Combos: 1312 (Including OS)

Okay here it is.

4890 > GTX 275
4890 = GTX 285
4890 CF = GTX 285 SLI
OC'd 4890 > GTX 285
OC'd 4890 CF > GTX 285 SLI

(By the 4890 and the GTX 285 being the same is because Ati loses in lets say 9 tests but wins in 8 (xbitlabs review), and for a $100 price difference, they are pretty much the same, anandtech did a review of the OC'd 4890 versus the GTX 285, the 4890 won. The links to reviews are below)

CF 4890 VS SLI GTX 285
http://www.xbitlabs.com/articles/v [...] 890cf.html

OC'd 4890 VS GTX 285
http://www.anandtech.com/video/showdoc.aspx?i=3555

http://www.newegg.com/Product/Prod [...] 6836121122

Good Speaker System

Good choice, but if possible wait for the 1GHz version of the 4890 to come out, and then you can still OC afterwards for an even bigger boost.

Would it? Possibly. Will it have a chance of not working? Possibly. Will it have a chance to destroy all your parts? Possibly.

The reason I recommended the 1KW Antec is because Antec is a well know company when it comes to power supplies, and it also allows you to save $40 when bought with the Antec 1200. Since you are getting that anyway (I assume) it'll be like spending $160 on the power supply. I did check the Corsair 750W and 850W, and really they had no good combos, or combos that actually worked with the items you got, but here are some other options:

Antec 850W
http://www.newegg.com/Product/Prod [...] 6817371024
$150

Corsair 850W
http://www.newegg.com/Product/Prod [...] 6817139009
$145 ($25 MIR)

I always like having extra wattage when it comes to my power supply, this leaves me room for upgrades and gives me peace of mind. You said you may crossfire in the future. A 850W will be taking a hard hit powering that, and the 620W will have no chance.

Really this is it - if you are getting the Antec 1200, get the combo which comes with the 1000W PSU and spend about $160 for a PSU that will last you a very long time.

I guess it's all up to who does the reviews.

Here we have gtx 285 > gtx 275 > 4890 > gtx 260 > 4870

http://www.tomshardware.com/review [...] ,2266.html

http://www.guru3d.com/article/gefo [...] view-test/

http://www.overclockersclub.com/re [...] a_gtx_275/

http://www.legitreviews.com/article/944/1/

Well I would suggest you get this PSU over that Antec...though it is not modular, but is one of the best PSUs around...
http://www.newegg.com/Product/Prod [...] 6817139009

And as for power requirements of the PC, are you going for tri-SLi ???Only then the 900W+ PSUs are required...
Actually for GTX 275 SLI/HD 4890 Crossfire, a high quality 750W like the corsair is more than suffice...And the 850W without question can power an i7 overclocked, 3+ HDDs, 2+ DVD drives, 5+ case fans, 2 of the above cards in SLI/Crossfire...

So dont overshoot the PSU as it is just waste of money getting such high wattage PSUs...

And as for the graphics card debate, both the HD 4890 and the GTX 275 have similar performance...
It depends more on what game you play...