Nice computer, but................it does NOT cost that much to get a computer like that!
Put it together from parts, or find someone who can if you can't do it yourself. You'll never thank yourself too much.
Here are the parts you want from your list (plus a motherboard):
$104.99 - ASUS P5Q Pro LGA 775 Intel P45
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131299
$167.99 - Intel Core 2 Duo E8400 Wolfdale 3.0GHz
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115037
$38.99 - OCZ SLI-Ready Edition 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227269
$99.99 - Microsoft Windows Vista Home Premium SP1 64-bit for System Builders
http://www.newegg.com/Product/Product.aspx?Item=N82E16832116488
$29.99 - LITE-ON Black CD/DVD Drive 24X
http://www.newegg.com/Product/Product.aspx?Item=N82E16827106291&Tpk=16X%20CD%2fDVD%20burner
$89.99 - Seagate Barracuda ES.2 ST3500320NS 500GB 7200 RPM 32MB Cache
http://www.newegg.com/Product/Product.aspx?Item=N82E16822148294
$109.99 - XFX PVT98GYDLU GeForce 9800 GT 512MB 256-bit GDDR3
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150316
Grand Total: $641.93
Of course, that does not include a case and power supply, but since you don't want any peripherals I assume you already have those too? Besides, I believe that all of these parts have free shipping.
Yes, quad core does make a difference. Not so much for gaming (until more games that utilize all four cores come out), but it still makes a huge difference for other stuff. I would just get the Q6600 2.4ghz quad core. I know it's what I have so I'm biased, but I've seen the charts and it is hardly behind the other way more expensive core 2 quad processors, and exceedingly cheap in comparison. It is also extremely overclockable. I don't recommend this, but a lot of people overclock it to 3.4ghz and beyond, which I may do in a year or two (or whenever I start to see a slow-down, which won't be for a long time). I payed about $189 for mine on NewEgg.
Quote: "It costs $1,174 but I was wondering if it would be worth it to just go ahead and get the Quad-Core Intel® Core™2 Q9550, 12MB L2 Cache @ 2.8GHz for $230 extra..."
Don't do it! Get the Q6600 for about $40 more. It seems it has gone up since I bought it several months ago, because it is so popular:
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115017
Quote: "If I was you I'd actually spend less, I'd just get one model down off the graphics card, use the ram from the old computer, perhaps get a second to join with it. Remove Vista and keep XP + service pack 3 til windows 7 comes out. Thus cutting your price nearlly in half along with having a brand new spanking computer state-of-the-art able to play anything still.
Practically every game will run on the older model for example my other computer (sitting next to me) is literally the same spec as yours except 5700FX Nvidia card, and it can nearly run any game.
Just trying to get the point across you don't need to spend x amount of money on something that can run things that haven't been made yet. (Which you'll be waiting so long before they're out that you might as well just buy the card then... at a much cheaper rate) Saving you money.
Yes you're computer seems like it's got great specs but do you really need it?"
I totally understand what you're saying. People spend way to much just for the "perfect gaming experience". But the thing is (as I have shown), you
can cut the price almost in half,
but still get the computer you want. The graphics card is not that new anymore and should be very affordable. I actually payed less for my system than you, n008, even though I got the more expensive Geforce 9800 GTX +, but I did already have vista, a case and power supply, and a CD drive, and of course all the peripherals.

It's a Q6600 2.4ghz quad core (runs GREAT), with 4GB ddr2 1066mhz RAM, and a 320GB HD.