Well, its recommended that you only have 1 virus program on your computer at a time because having more than one can cause them to interfere with each other causing even more slowdowns. Also about the "preemptive multitasking" win XP dose that but it just dose it on every single program that you open. But I do wish that there was a way to program an OS to show you whats making your computer so slow.

Quick Question
When you open the task manager and click the Performance Tab. Under CPU usage what dose it say. Try to give me about and average when you're not doing anything on your computer then open up your internet browser and then let me know what that says.
Tech TJ