You need anti-virus as well as adware to be fully protected. You dont need a million programs as was said before AVG is one of the "free" best but certainly not the best by any standard. I had a Windows Xp Security background and it was a virus that disabled my windows taskbar so that i was unable to launch any programs, my desktop items were hidden also.
AVG found the virus but couldnt take any action. Adware was able to delete it tho whereas AVG couldnt.
So in terms of free
1st, download AVG http://www.download.com/AVG-Anti-Virus-F…
2nd, download Adware http://www.download.com/AVG-Anti-Virus-F…
When both are installed, run a full system scan starting with AVG then use Adware afterwards to detect any viruses that may have been hidden.
McAfee Site Advisor is a recommended tool for virus protection also, warns you against sites with potential viruses. Just added safety for your computer.
after reading to decide if its wat u want and you can begin to download