your better off goign with a intel chipset because nforce chipsets usualy have bad vdroop and atm do not overclock aswell as the latest intel chipset p45.
this is the best price/perofrmance build u can get atm.
Newegg.com - Intel Core 2 Duo E8500 Wolfdale 3.16GHz 6MB L2 Cache LGA 775 65W Dual-Core Processor - Processors - Desktops
or quad core, depends, some think quads could be alot more future proof once they become usefull for gaming, but since you dont game alot and just want it for other things a q9300 could be worth youe while, ur decision. ntoe that rendering videos and cad etc will be alot faster on a quad. the other conflicting thing is, the cheap quads like q9300/400 are often bad chioce for overlcockign since they have low multis, this has a 7.5x multi so to reach 3ghz u would need a 400 fsb. this would be easy ojn the p45 chipset, but at about 3.4-5 will be hitting a wall. this is why the dual cores are so good atm (e8XXX). but hey, that quad at 3.4 will be fine anyway.
Newegg.com - G.SKILL PI Black 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Desktop Memory
Newegg.com - BIOSTAR TPower I45 LGA 775 Intel P45 ATX Intel Motherboard - Intel Motherboards
Newegg.com - SAPPHIRE 100245L Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Desktop Graphics / Video Cards
or 4870/core 216 if you have the cash, but since ur not gaming alot its a waste becuase it will outdate too wuickly for the money.
same hdd, case (what u like) etc..
those main components are great, that mobbo is much better chioce than a 750i which are not good at all from what ive heard.