My goal was to build the best PC possible for $500 - capable of handling video recording / rendering and light gaming. I don't think many people would dispute that Intel makes the best chips on the market, but I found that the best bang for my buck was definitely with AMD. The six-core processor I selected had a noisy and ineffective stock cooler so I invested in an aftermarket cooler that I have been really really happy with - keeps my chip running really cool without noticeable fan noise. I chickened out and used ceramic thermal paste (albeit a highly reviewed brand) because I didn't trust myself to avoid smearing some on the motherboard. I splurged a bit for the SSD drive that I installed my (questionably legit) copy of Windows 7 Ultimate x64 on but I think it was worth it - this machine is usable at the desktop in under 30 seconds from a cold boot and Windows / Sony Vegas runs incredibly fast. I'm really happy with how everything came together and with the performance I've been getting for the price!
Edit: My parts list didn't include the aftermarket cooler I used so I added that.
Also, the build total says $600 but when I purchased the parts the total was actually around $500. You can see if you look at the total price fluctuation under the completed build.
Also added a shot of the inside - I know the cable management is horrible. :P
I think I'll add a PCI-E card with 6g/s SATA ports.