Worm, Or Slow Computer help

I HAVE BEEN TRYING TO FIX MY COMPUTER FOR LAST 2 MONTHS!!! BUT ITS NOT WORKING??? I HAVE TRIED DOING SEVERAL THINGS....defragmentation...restoring...cleaning old files...download many softwares that deals with viruses...Ad-ware..cleaning my temp internet files...I think i have done it all and still my computer is not speeding up??? what to do???..I think when ever I open my computer their are many programs who open it self up!!! by using a task manager I have tried to End the process...but still the slowness of my computer is remand???? what to do???HELP

some of the things that I see in my Task Manager are:
smss.exe(SYSTM)
svchost.exe(4 OF THEM IN :SYSTEM) THE OTHER 2 ARE RUNNING ON LOCAL SERVICE AND NETWORK SERVICE
isass.exe(SYSTEM)
winss.exe(SYSTEM)
service.exe(SYSTEM)

I have run Ad-ware..
I also had Spybot 1.3 but I uninstall it and tried to install 1.5..but I'm not successful doing that...
I have rum SpyDoctor..which sayed I had 297 problems...but it couldn't fix them...
I have run WindowLiveCare..which haven't found any of the viruses????
I have cleaned up my registry keys
I have run c clener
I have deleted all my TEMP folderss

Now still my computer is very slow and the internet is also slow????:confused