For $300 a 660Ti is probably a better option now, though I'd wait till the price stabilizes, it just came out so they're probably inflated a bit.
EDIT: I'd also consider a 7 series chipset for the motherboard, Intel just released an update that passes through TRIM commands for SSDs for RAID arrays, so you can RAID 0 two SSDs for almost double the performance! If I was building I'd definitely consider getting 2 128GB or 256GB instead of 1 265GB or 1 512GB.
http://www.anandtech.com/show/6161/i...rds-we-test-it
1,100MB/s!