Microsoft Silverlight = Virus?

I just had a 'fun' experience revisiting an old friend, Windows XP. I don't personally use XP, or any version of Windows, but was trying to clean up an infected computer. Here's the story.

To watch the Olympics online through Firefox, you need to install Microsoft Silverlight. Not only does this allow you to watch all the genetic super-humans competing for the illusive gold, you also get frequent Internet Explorer pop-ups displaying ads and new videos sites! The pop-ups seem to be a result of a randomly named process that reinstalls itself into the Windows/system32 folder as a randomly named .exe and .exe_a_a (or something similar) file. To remove this, I used the Spybot fileshredder to delete the files immediately after killing the process. It would probably be easier to do this in safe-mode, but I completely forgot there was was such a thing (too many years using Linux).

What bothers me isn't the virus or spyware, but the fact that neither McAfee, Spybot, nor AdAware was able to identify let alone fix the problem. It seems like this would be a very simple problem to detect and prevent or delete. I don't want to turn this into an anti-Microsoft rant, but I don't trust Windows. This is partly Microsoft's fault, for making an insecure operating system, but I also blame McAfee for not picking up the problem. I had better luck using Spybot, a free tool, than McAfee.

I imagine there are programs that can make Windows XP more secure and less prone to such infections. Does anyone have any suggestions or know of a good website where these types of programs are compared or reviewed?

oh... use Ubuntu :) it's safe, easy, powerful, and fun... the way computers should be