System maintenance allways helps out when you do it. It sound like your doing all the right stuff, but do you scan for virus or spy-ware? Spy ware can really slow your system down alot. I use
Ad-Aware and
Spybot-S&D to check for spy-ware each weak. Also keep up with the windows patches, their so many new virus out where that everyone should turn on Auto Update or go to
Windows Update at least once a week.