^Like He said, clean the stuff, or consider a new mouse/new mouse pad. If you're a gamer and have been eying some gaming mouse/keyboard for a long time, now's your chance. (Just for the record, SteelSeries has the best stuff.)
Check up on what programs are running in the background, and try closing them. These include instant messengers (AIM, ICQ, GTalk, XFire, MSN Messenger, ETC), Torrent Programs such as MuTorrent, and usually AntiVirus.
Lots of those programs run when you start the computer, so go in the options and shut that off. Those put a significant drag on boot time.
Also, running too many applications at a time, like having three firefox windows (not tabs) open or having an emulator, maplestory and firefox running, or any number of applications usually isn't smart.
Run CCleaner and AVG (Google them.) Run Windows Defender (which came with your PC). Run Windows Updater.
If all else fails, you've got two options:
-Buy More Ram or a better processor
or
-Re-Install the OS/Upgrade/Downgrade. If you're changing the OS do NOT change to Vista, try XP. But if you already have vista then it's ok to keep it.
Also, are you on a laptop, a netbook (mini-laptop), or a Desktop?