Spyware, Adware and viruses my constant menace.

It is interesting to view taht spyware and adware seem to target one of the two computers that I own over the other, both computers are relatively the same age and contain similar processors and both have many antiviruses spyware and adware sites, however one is primarily used for games, surfing etc and one is used for work and uni work only. After this it is possible that it generates thoughts that simply because I am accessing sites with lots of spyware adware on them, however it is the computer that I almost solely use for uni work that is constantly infected and requires reformatting, i have 5 or 6 antivirus/ spyware removal programs and these do not seem to work properly and increasingly bad performance is occuring for this computer. I have no idea where this is coming from but it is causing me constant problems rather then being a minor hassle as it is on mmy other computer.