security shit

well all the time windows security center pop up these yellow alert things about spyware, that someone is looking for my credit accounts, trojan is infected, someone has control of my computer, privacy at risk etc. and it happens about every 20 second and it says it that I should do full system scan and spyware scan and stuff and just did all of it but it still keeps going on, and it also opens explorer to their homepages about windows security centers programs that I also downloaded and ran but wtf it still keeps going on....is this some windows commercial spam(cos they want me to buy their spyware programs) or is it really virus, well I know u cnat know that but just wondered if anyone have had the same problems. And also how I can make it stop, I dont wanna go and play ET and come back in windows with 70 internet explorer pages open LOL, and that laggs me down every time they open....