Lavasoft do a free download called Ad Aware.

It enables you to seek out and delete the Data Miner programs installed when you visit web sites.

These rascals collect info on what you've looked at and pass it on to herberts whose sole purpose in life is to generate Spam.

Have a look at the above, you'll be surprised at how much stuff is sitting in your PC that you weren't even aware of.

Bestest Regards, and Good Luck....

Ian Darby.

P.S. Also see Zone Labs 'Zone Alert' free download.