Cleaned out viruses but still have problems?

I have a XP SP3. I got a few viruses and malware and luckily Spybot S&D found what they were and deleted it but I wrote down what they were anyway. I did a search for the viruses and I ended up installing Spy Doctor and Stopzilla. That found more and fixed them. I have McAfee as my main antivirus. After cleaning out as much as I could find with those 4 programs I still have a few problems. Just right now I heard through my speakers "Congratulations you won". Now I'm hear an advertisement for something. Nothing pops up and I don't know where it comes from. I also notice my system is a lot slower. It takes forever for my scanner programs to run. I hear a clicking every so often like when you click something on the net, but it's not me. I also get an prompt saying that IE is not your default browser would you like to make it your default. I get that when I'm not even connected to the net. Sometimes I can't hear anything from my speakers. So I got to Control Panel/Sounds and Audio Devices/Advanced and I noticed the Wave slider is all the way low. All this happened Wed. night and I have been trying to fix it since. Something really F'd my sys up. Any help would be great. Thanks.