Cannot update computer, load Norton, etc

Have a computer that had alot of virus’s and infected files. I think that is a taken care of now, but I cannot load Norton, cannot do a Microsoft update, some thinks do not work when going to Symantec’s site and things like that. I know it has something to do with the virus’s that were on the machine. (about 1000 infected files with, trojans, W32’s, etc.

What do I look for as to getting IExplorer working properly.

Have reloaded windows and even upgraded to 2000, that did not help any.

Thanks