Oh, forgot to mention. Pick a good case! To ensure the reliability of your PC, you need a case with good power supply (some case don't include them, especially the highend ones) and air flow. Most generic cases have really bad built quality, the sheet metal is paper thin. I had a generic case made by tsunami, it would start vibrating when I use the DVD-ROM. For an affordable "good" case, look for an Antec (e.g. SLK-3700).
http://www.antec.com/us/