the core i7 870 surely may not the best start for the ideal/affordable build, but it was a gift, so it's what I got.
The i7-870 is overpriced. I would use a 750, and OC that, and repurpose the money towards a nice USB 3.0/SATA 6.0gbs and a 5970.
Wow, reading the OP before posting a reply is usually recommended.
Here's my suggestions.ASUS P7P55D-E Pro LGA 1156 Intel P55 SATA 6Gb/s USB 3.0 ATX Intel Motherboard - Retail
$189.99CORSAIR XMS3 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CMX4GX3M2A1600C7 - Retail
$114.99Microsoft Windows 7 Home Premium 64-bit 1-Pack for System Builders - OEM
You don't list gaming. Will you be gaming at all on the system? If not, a 5770 would be plenty. A 5850 would be best if you want to game.http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.335363
$159.98 - $15 MIR (Antec 300 illusion + Antec EA750 combo)