I already have some things like a hard drive, mouse, keyboard, CPU cooler (hyper master 212+ which is compatible with all the AMD and Intel sockets), OS, and of course my TV. What I need is: case, motherboard, CPU, GPU, PSU, and memory. I'd like to keep it under $450 for those things, but the cheaper the better so long as it does everything I need.
I also looked around a bit - it looks like if I do go with an AMD build better to get an ATI based card as they seem to play nicer than with Nvidia (probably because AMD/ATI are the same company). What's also nice with ATI is many more of their cards seem to have HDMI out and HD audio bit-streaming, which are essential for my HTPC use.