I've got a similar system to Sirwoolley, and am happy with it.

Asus P6T (x58 chipset)
i7, 920, stock speed.
12gb ddr @1600mhz.
Antec 900 gamer case.
Nvidia GTX 275 (896mb)

Recently got Win7, but have not finished backing up C drive, so haven't put it on yet.

And have a shiny new SSD (Patriot Torqx 64gb) which has wow on it now (getting 200mb/sec read, they advertised 220, so close enough). I like that they offer a 10yr warranty on their drives.