If you want your computer to last longer get a quad. the Q6600 is a good price. Plus you can o/c from 2.66 to 3.0 easy on stock voltage. or to 3.2 or 3.6 if you really want. some games use the quad-core some dont. i mean if you think the E8400 will work for what you need get it. but since your talking about making your computer last longer get a Q6600
It's not going to last longer if he only to continues to use single or double threaded apps. the Q6600 would be much slower then a E8400 for those types of apps.