IMO, both Norton and McAfee are poor ( I'm being really, really polite!).
AVG is much better.
Tater, do you have a firewall installed and running? If you don't, you need one. The Windows one that is part of XP is ok, and you may already have it. Zonealarm is another free firewall that works.
The big thing is for you to get antivirus and a firewall up and running.
Another resource, maybe, is a lot of the people that make and sell antivirus programs have a website that will do a free scan for you, on line, if you can get to them. PC pitstop is one such place.
http://www.pcpitstop.com/default.asp
If you can get those downloaded, or get copies on CD from someone, take the PC off line and try to install AVG and have it scan everything.
AdAware, by Lavasoft is good for catching spyware too. There's an even better program called Spywareblaster that sort of does the same things as AdAware, but catches the stuff before it gets on the PC- it's free and works extremely well.
http://www.javacoolsoftware.com/spywareblaster.html
Tater, all the programs everyone has mentioned are very well known and will come up right away on a search.
If none of this works, I'd make a call to the local independent repair shop- look for a little 1-2 man place. NOT a place that sells lots of name brand computers. When I had a problem quite a while ago, my local shop made me a copy on CD of all these programs and gave it to me.