Why is my computer slowing down?

When i first bought my computer, it was nice and fast - no delays on start-up, or when opening programs. Now, it's like a grumpy old dinosaur, and refuses to do anything at more than half the speed it used to. I regulalry scan with McAfee and other spyware detection/virus removal programs. I also have plenty of free memory, and regularly defragment my hard-drive. My computer is only just over one year old... any suggestions on what the problem might be, or how i can fix it?

Why is my computer slowing down?kawasaki

Mcafee will slow down your PC and it certainly doesnt catch all spyware.Spyware will slow ot down.

Here is a list of free scans.I would recommend running ewido first.

Spybots search and Destroy http://www.download.com/3000-8022-101221...

adaware se%26gt; http://www.download.com/Ad-Aware-SE-Pers...

http://www.webroot.com/land/freescan.php

a-squared Free%26gt; http://www.emsisoft.com/en/software/free...

http://housecall.antivirus.com/housecall...

http://housecall65.trendmicro.com/

X -Cleaner Micro Edition scan http://www.spywareguide.com/onlinescan.p...

http://www.kaspersky.com/virusscanner

http://www.windowsecurity.com/trojanscan...

http://www.bitdefender.com/scan8/ie.html

http://www.pandasoftware.com/products/ac...

http://www3.ca.com/securityadvisor/virus...