With that kind of budget you can afford an SSD for your system drive along with alot of RAM. I have both and an ASUS motherboard with dual GTX-460 video cards. The CPU is an i7 960 @ 3.20GHz. I used 24GB of triple channel RAM. I like to keep my drives under 2GB and I have an assortment internal and external. I don’t have a raid, for the time being disk speed is not a bottleneck for me.
Hope this helps,
Jeff
http://www.narrowroadmedia.com