You have to watch out.

99% of the "free" anti-virus and spyware programs are spyware in themselves. They might offer some relief from the virus that is causing you grief but they are not as they appear.

Nothing is free in this world my friends and companies don't make anti-virus software just to be good Samaritans.

When you install a "free" spyware/anti-virus program, you are simply substituting a less destructive malicious software that may offer some relief from the problems you are experiencing but your computer is still infected in a more stealthier way. They are for suckers.

You have to pay and keep your anti-virus software up to date if you want to be truly free of unwanted infections.

Another way to do it is to re-install everything from scratch and then before you go online, back it all up on another hard drive. Then if you become infected again you can simply clone the clean drive and you'll be free again with the original blistering speed.