The problem with disabling & leaving NIS installed is that a lot of times the hinkiness in that program is in the anti-virus portion of it. Disable only disables the firewall, leaving potential conflicts still running.
Adware & shareware would slow everything down, but I don't think I've ever seen the level of problems Ex-Wretch seems to be having.
I think Norton can all be disabled via msconfig.
I don't disagree, but disabling it temporarily might work, and if it does we will know that NIS is the problem. Also, this can be done very quickly.