Along this get a decent firewall. Comodo firewall is pretty sound, it conflicts with Avast sometimes. Not sure if it does now but it gets fixed fairly quicknew question:
currently im using following programs to keep my computer clean and updated.
AVG 8.0keep if you want, I prefer Avast
Eusing Registry cleanerditch
Does your PC run quicker in safe mode, if so it's something your computer is loading in system tray when it's switched on which will be all the programs above
Turn off windows visual themes. They're rubbish and hog loads of memory / cpu usage.
Clear any temp files inside of windows and recycle bin
Defrag hard drive
Should help speed it up