No worries. I was thinking the same when I was getting ready. If you are not concerned with SLI than get this board for crazy OC on the 6420 and with an aftermarket cooler (tuniq tower, artic freezer pro 7) you will get very good OC on that CPU.
GIGABYTE GA-P35-DS3R LGA 775 Intel P35 ATX Intel Motherboard - Retail
No need to get 4gb RAM unless you are doing CAD or Video Encoding and such. 2GB of that GSKILL HZ RAM will do more than enough for gaming.
As for the Raptors in RAID. Complete overkill. Just save alot of money and get the 2 Seagate 250 or 320gb SATA drives and RAID them its about equal to 1 Raptor and gives you 2-3 times or more storage.