Is this a good i7 920 build for gaming?

By 925 do you mean 295? If so, get a 5870 instead.
Then get this HDD
SAMSUNG Spinpoint F3 HD103SJ 1TB 7200 RPM 32MB Cache SATA 3.0Gb/s 3.5" Internal
http://www.newegg.com/Product/Prod [...] 6822152185

And this PSU
Antec TruePower New TP-750 750W Continuous Power
http://www.newegg.com/Product/Prod [...] 6817371025

this RAM
G.SKILL 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Triple Channel Kit Desktop
http://www.newegg.com/Product/Prod [...] 6820231230

and the P6T SE
ASUS P6T SE LGA 1366 Intel X58 ATX Intel
http://www.newegg.com/Product/Prod [...] 6813131386

Then this HSF
COOLER MASTER Hyper 212 Plus Intel Core i5 & Intel Core i7 compatible RR-B10-212P-GP 120mm "heatpipe direct contact" Long life sleeve
http://www.newegg.com/Product/Prod [...] 6835103065

You can probably drop the sound card as well.

By it I mean current ATI cards.

Why did you throw the ATI card out? Cards have warranties you know. 5870 is a way better option than the 295 BY FAR.

Definitely get the HD5850 1GB. There are many reasons including the 26W idle power which means it's very quiet when non-gaming. It's also future-proofed.

1366 uses a Tri-channel configuration. You should be getting 3x2GB or 3x1GB. There won't be a huge difference but I'd lean towards the 6GB total.

FYI, there are i7 CPU's on both the 1366 and 1156 but they are NOT compatible. For example, the i7-860 will NOT fit on a 1366 board.

No, you shouldn't. The 900 comes with case fans.

At this point in time, ATI clearly wins the price / performance battle up and down the various points price points with two exceptions....the 260 and the 295 at least according to review sites like anandtech.. The 295 still is top dog and only you can decide if the extra $80 for the performance increase is worth it in the games you play at your resolution. The 260, the 4870 and the 5770 are all running around the same price / performance range....again, see the anandtech site for details.

However, remember that ATI's 5xx series now supports DX11 and nVidia's current offerings do not. If you don't keep GFX cards more than 2 years, this probably wont be an issue for you as it will be at least 2 years before Dx11 becomes significant. Just because DX10 was a complete dud, doesn't mean Dx11 will be, only time will tell.

The other consideration is PhysX....does it matter to you ? If you judge by Mirror's Edge, you will probably yawn. Then if you judge by Batman, you may be intrigued. Personally, i find the effects impressive, at least how hey were done in Batman. But again, if game developers invest like Batman's developers did, I'd exect PhysX to be a consideration to many buyers. If it gets implemented like it was in Mirror's Edge, it will be another Dx10.

http://www.firingsquad.com/hardwar [...] /page2.asp

The price between the 295 and 5870 is as narrow as $80 on newegg (and much more for tweaked versions), so you will have to decide if the performance difference and PhysX is worth it to you. However, you shouldn't be basing your primary GFX card decision on PhysX.

http://www.tomshardware.com/news/n [...] ,8786.html

This patch lets you use PhysX while running ATI cards as your primary hardware.

As for the rest:

-HD - get a 500 Gb per platter drive
SC - if you're thinking "sound card" consider the Asus Rampage II Extreme MoBo whih -comes w/ a Supreme XiFi daughter card and some nice OC features.
-Suggest Antec TP or Corsair TX series PSU amd Antec 902 / CM 922 as an option in single GFX configuration (650 watts)
-Suggest Antec SG or CP series or Corsair HX series PSU in dual GFX configuration (850 watts) in an Antec 1200 or CM HAF 932
-Look at these for HSF's
http://www.frostytech.com/top5heatsinks.cfm
http://benchmarkreviews.com/index. [...] itstart=15
silentpc.com see cooling / heat sinks (site down atm)