slowing to turtle speed

my pc has been getting consistenlt slower by the month and I can't figure out why, I know there are alot of files on my hard drive, must have at least 20-30 hotfixes showing for windows xp and 15-20 security updates as well are all of these necessary to leave or can they be deleted after the new one has been installed, also i have spyware and adaware, what else can I do to check pc health, i tried the pc doctors but they werent free, and i have deleted cookies and all of the internet stuff, a little help please, what else can i do to speed things up?

Are u running on 128 RAM or less? If yes, adding more will definitely help improve speed.
Whts the HD capacity? Check if thts running out of space, running a disk clean up ( you can delete the temporary files, empty recycle bin, older restore points etc) and defragmenting it regularly will help keep it fast and smooth. Especially since nowadays loads of carp** gets dumped into the system even after browsing sessions. You could also disable unnecessary items from your startup list. Of course ensure the system is free of spyware.
check out the following links
To free up disk space
http://pcworld.about.com/magazine/2007p162id97442.htm
System slowdown
http://www3.telus.net/dandemar/slowcom.htm
http://www.microsoft.com/AtWork/getstarted/speed.mspx/
http://mywebpages.comcast.net/SupportCD/OptimizeXP.html

Hi, i like to use this program for cleaning…….

http://www.stevengould.org/software/cleanup/

If you use this under options check standard………….

thanks for the help ill let you guys know how this goes