|A quad core is definitely overkill for the intended use of the system.|
The Core-i series is the latest from Intel, but you could get off more cheaply by building an AMD system. Also, you can save yourself some money by NOT installing a video card. As long as you're not into gaming, onboard graphics should be sufficient. Even so, if you go for a Geforce GT 240, get one with GDDR5 memory, not DDR3. And I would avoid Cooler Master PSUs unless you get into the GX series.
ECS Black Series A785GM-M - $55 after rebate
AMD Athlon II X2 245 Regor - $60
Patriot 4GB (2 x 2GB) 240-Pin DDR3 1333 (PC3 10600) - $35 after rebate
CORSAIR Builder Series 430W PSU (+12V/28A) - $37 after rebate
SAMSUNG Spinpoint F3 500GB 7200 RPM 16MB Cache SATA HDD - $50
And don't forget to benchtest!
How to Bench Test Your System