Carbon, while that's not a bad idea, it's not exactly weekly maintenance - I wouldn't check my temperatures and place fans by my computer once a week to see if it ran faster.
Chris - my maintenance is defrag with JKDefrag, CCleaner to clean junk files and the registry, NTREGOPT to optimize my registry, and Bootvis to keep the boot time low.
Some people will doubtless disagree, but I've personally found this to be the best combination of tools, along with security, to keep my PC in good shape.