Man I'm surprised every time I look at it just how much of a resource hog Norton is. I'd dump it immediately and get
AVG. You can also disable startup processes for things like real player, quicktime, and acrobat. They run in the background hogging resources just so the program starts faster when you try to open it. Go to Start > Run > msconfig > startup tab to access it. If you're really ambitious goto Start > Run > services.msc and read the descriptions of/google services set to "automatic" to see if you can downgrade it to "manual" or "disabled" (I'm talking things like spoolsrv.exe that you obviously don't need if you're not running a printer).
Also, get
hijackthis and run the log file through
here.
You can post the log here too, it helps a bit more than just a list of running processes.