processor - core2duo or quad core
mobo - intel or [asus/gigabyte- if u wanna overclock
ram - 2gb800mhz / 4gb [if ur going with 64bit os
power supply - 500w or better[ amacrox / asus ]
vga - [9600gt,9800gt,GTS250,GTS260 - Nvidia] [ 4770,4850,4870 - ati ] or better
H.D.D - watever capacity u like [sata
opticle drive - dvd r/w sata, lightscribe..
gud casine with enough internal space