Apart from the obvious mentioned above, I would recommend going to.......
Trend Micro HouseCall - Start
This is a great little site which will get rid of all those nasty infections. Bookmark it and you will always go back.
For computer maintenance I also recommend a great utility called
TuneUp Utilities 2006. It's not completely free, as you have a 30 day trial. But its great to use within that time, and you could buy it if you want (Worth the money) It does everything, and I mean everything.
I also use
CCleaner , Ad-Aware, And Mcafee internet security suite.
I do have one question and that is, do you think I should use any other software apart from just Mcafee to protect myself? Or is the security suite good enough on its own?