I've heard mixed reviews of iBuyPower over the years. They have been around a long time though, and Newegg sells them. I'd do some serious internet searching, asking on relevant forums, etc before I put out money though. Particularly find out what their warranty terms are and how responsive their jan support is. I've heard some good reviews of this place:
http://www.uberclok.com/ - worth looking into.
That CPU is overkill for gaming. Either one of the quad Core i5's (careful - some are duals, some are quads, get a quad), or one of the 800 series Core i7's. Only reason to get a 900 series i7 is if you do video editing or like throwing away money. The AMD Phenom II's are very good as well, and a little cheaper.
Do not get water cooling unless you have a real reason to need it. The only good reasons are insane overclocking, or living somewhere where the ambient temperature is pretty high. The current generations of Intel and AMD chips run pretty cool and don't get terribly hot even when running fully loaded. A good 3rd party CPU heatsink and fan are recommended though, as is good case cooling (ie lots of fans).
Ditto Kera on the RAM, 6-8GB is preferred for new systems, 4 at a minimum. DDR3-1333 or 1600 doesn't matter too much unless you're overclocking.
Radeon 5850 is hands down the best video card for the money right now; 5870 if you want to go high end, or 5770 if you're going to be playing below 1680x1050 res. I would only buy an nVidia if you intend to spend a great deal of time playing specific games that benchmarks have shown nVidia to have a significant advantage at. See Tomshardware and Anandtech for such benchmarks.
A GOOD POWER SUPPLY IS IMPORTANT - not some no-name brand. Make sure you get a good one. Corsair, Silverstone, Antec, BFG, some of the Enermax, FSP Group, Mushkin, OCZ, some of the Thermaltakes, and PC Power & Cooling are known good brands. OEMs like to skimp on power and it can cause all kinds of problems. Invest in a decent PSU and you'll be a lot happier with a stable system that has a decent lifespan as opposed to dying from brownouts on a $30 PSU.
Hard drive, who cares, your choice; I don't see a need for anything >500GB, but TB's are cheap, go for it. If you're looking for high performance and have VERY deep pockets, an SSD for an OS drive is a good choice - recommend minimum 64GB, and high read/write speeds to make it worthwhile.
I'd recommend dual drives, a BD-ROM and DVD-RW. You don't seem to care about saving money, and Bluray is the Next Big Thing - if your monitor is going to be 1920x1080 or greater, might as well be able to watch HD movies.
Sound is unimportant unless you're an audiophile, modern CPUs being multicore don't have the problem of slowing down a lot while doing sound processing like some old systems did. MS kinda screwed EAX since Vista, so Soundblasters don't offer the advantage they once did.
Do yourself a favor and get a decent monitor - good color quality, 1080p most likely - HDMI is desirable from a forwards-compatibility standpoint, but not essential. There are plenty of good brands, just read some reviews before you buy so you don't get a lemon.
You left out keyboard and mouse like they didn't matter. They are important to any serious gamer. My recommendations are wired, laser, lots of buttons for mouse (like my Logitech G5) and something that doesn't suck for keyboard (Logitech or Saitek gaming keyboard).
My exceedingly useful resource, up to date as of a month or two ago:
http://macgamesrule.webs.com/comp%20config%202.html