AMD A10-6800K APU 4.10GHz
8GB RAM
1TB HDD
Windows 7
No CD/DVD drives. This was the first computer I built for myself, so I was trying to keep costs down as much as possible (which is why I went with the APU processor, which I think I got on sale as well). Not including the OS, the cost was around $350 for the whole setup ($450 adding in Windows 7).
I got a spare Dell monitor from my dad and bought crap cheap speakers, keyboard, mouse, etc., so maybe around $500 after tax for everything? It's not a beast computer, but it runs fast for what I use it for and I put it together myself with no experience, so I'm happy
