To make sure everything is running fine run both anti virus and anti spyware apps in normal AND safe modes. (make sure that they are updated first !

) (
AVG is good and free AV)
(A couple of good removal tools are
Spybot and
Adaware)
ALso an on line virus and spyware scanner is
Trend Housecall
Just a note; actively running two AV's on one machine can cause problems.
So if you are thinking about it make sure your current one is disabled first.
SAme thing applies to online scanners as well.
Removal of junk files is easy with
CCleaner a free app that does exactly what you need.
Part of CCleaner is an uninstaller, it is advisable to remove any programs that you are no longer using.
Also check to see what is loading at start up.
As a rule of thumb they only apps that should load on start up are security ( anti-virus) and connection apps.
Other start up apps are up to you, but if you don't use it all the time then make sure it doesn't load on start up.