remove any programs you dont use to free up some space on the hard drive.then check what programs are starting with windows.
click here for a list of start up programs.
click here for windows services that can be set to manual start or disabled to free up some resorces.
also try spybot click here and adaware click here to check for spyware.
update you antivirus and run it.
update all your drivers for mobo and graphics etc.