Hi
If you don't know how to use registry cleaners, and do a full AV scan with system restore turned off, clean out all temp files, and use hijackthis, you will need help. There is not the one piece of software that will help much in this situation. Get some help, backup documents and get Windows reloaded. If you have a restore disk or Windows and it's product key .. all the better.
Sounds like you are either 1. Infected with adware 2. Bogged down with resources being used up due to various running processes 3. Hardware issue ... or a combination of all.
Rgds. Al.