First time build questions

[KingHos]

Im trying to build my first pc and I know very little about them because Im a mac user. Im trying to build a budget gaming rig for around $500. So far ive gone on newegg and looked at the parts and the ones below are the ones Ive narrowed it down to. Any suggestions or things that someone with no pc experience should know? Are the parts compatible? My budget is about $600 not much room for improvement. Im not sure if i need a case or not so any suggestions would be nice.

Motherboard:Gigabyte GA-K8N Pro-SLI Socket 939 NVIDIA nForce4 SLI ATX AMD Motherboard - Retail

cpu:AMD Athlon 64 3200+ 2000MHz HT Socket 939 Processor - Retail

Hard Drive:Seagate Barracuda 7200.9 80GB 3.5" SATA 3.0Gb/s Hard Drive - OEM

memory:CORSAIR XMS 1GB (2 x 512MB) 184-Pin DDR SDRAM Dual Channel Kit System Memory - Retail

Video card:ASUS Geforce FX5200 V9520-X/TD/128 Video Card - OEM

cd drive:SONY Black IDE DVD-ROM Drive Model DDU1615/B2s - OEM

sound card:SABRENT SBT-SP6C Sound Card - Retail

power source:COOLER MASTER eXtreme Power RS-430-PMSR/P Max: 400W, Peak: 430W Power Supply - Retail

[Alaron]

Welcome to PCMech.

There's no need for that sound card. Onboard sound is adequate on a budget.

Second, skip the FX5200, its very weak. If you're gaming on a budget, look at the Radeon X800GTO. The best bang for the buck card right now.

You can score a great case and power supply combo with the Antec Sonata II.

Don't forget Windows XP.

If you don't plan to use SLI, you can save money buying a non-SLI board. The Asus A8N5X is excellent.