I just built one, build is as follows.
Cpu : q6600 @3.2 ghz thermalright true idle : 37 load:56 @ 1.32v
Ram : Corsair 4096 pc2 6400
Motherboard : Abit Ip 35-pro
Case : Silver Lian -li PC-V1000
DVDRW - LG lightscribe generic
HDD - Samsung F1
Videocard - 9800gtx +
Installation, setup and updates will take about 4-5 hours.
Its tedious. But it can be done.
If you are going to dual boot, you will simplify your life ALOT, by having two hard drives.
Ideally you would have one 74 gig raptor per os (cheap and effective), and a 750gb hdd. for storage.
insanelymac is a great resource, for this.
Everything works in osX except waking from sleep. Mild annoyance. Total build cost including the ACD 23" was 1300.00
You don't need any additional hardware, just stick with intel chips.