Hi there r0bbin! Let me answer your sound card question first:
You normally don't see a sound card in a build because the onboard motherboard sound card is normally enough for a normal gaming computer. The quality is good and there is no need for a discrete sound card.
I would recommend this setup if you don't plan on overclocking:
CPU: Intel i5 2400 $190
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Graphics: EVGA 012-P3-2066-KR GeForce GTX 560 Ti (Fermi) 448 Cores $290
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
MoBo: ASRock H61M-VS $60
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
PSU: OCZ ModXStream Pro 500W $65
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Case: NZXT Gamma $40
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
HDD: Seagate Barracuda 500GB 7200RPM HDD $85
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
RAM: Patriot Signature 8GB (2 x 4GB) $35
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Heatsink+Fan: Stock $0
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
DVD-ROM: Samsung 22X DVD burner $17
Total: $752
Explanation: The i5 2400 is a great CPU, it is on par performance wise as the i5 2500k but without the ability to overclock, it is also cheaper than the i5 2500k.The 560Ti 448Core is a weakened gtx 570, it is a great graphics card with the ability to play any modern game. The ASRock board is decently priced and is perfect for what we have.The 500W PSU is more than enough for the graphicsc and the computer components. The NZXT Gamma is a gaming case, it was designed for long graphics cards and such, so you should find no problem squeezing 10.5" gfx cards into the bay of the NZXT GAMMA. The 500GB HDD is for storage, I would not recommend any HDD with higher storage since HDD prices are though the roof. 8GB of RAM is more than enough for any gaming system, you'll almost never use all 8GB of the RAM. The DVD Burner is to watch DVDs and install Win7.
If you want to OC, then go with this system instead:
CPU: Intel i5 2500k $230
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Graphics: HIS H687FN1GD Radeon HD 6870 $160
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
MoBo: ASRock Z68 Extreme3 Gen3 LGA 1155 $122
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
PSU: OCZ ModXStream Pro 600W $75
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Case: NZXT Gamma $40
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
HDD: Seagate Barracuda 500GB 7200RPM HDD $85
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
RAM: Patriot Signature 8GB (2 x 4GB) $35
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Heatsink+Fan: Stock $0
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
DVD-ROM: Samsung 22X DVD burner $17
Total: $764
Explanation: The i5 2500k is more expensive, but can overclock. I had to make some cuts on the graphics card because of the budget, if you can afford, I would recommend you go with the gtx 560Ti:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
The ASRock board supports the new PCIe 3.0 slots, and can support CF and SLI. The PSU is the same brand and model, but it is 600W instead of 500W. Everything else is the same