The IP address thing. Without making things complicated I run three seperate lines into my place. One is DSL one possible way of changing my IP in a hurry if I have to is disconnect the line for around 30 min and reboot.
But you have two PCs why not get another line hook from a different company thus assigning a new IP. Plug one line in for one IP plug the other one in for another.
This chatter is a bit sensitive. This is one way of doing it without disrupting evertything else you have going under your current IP.
Also check your registry for any keys that may have been installed by overture. If you find any delete them. Companies just don’t always track IPs they also somtimes install Reg keys and other stuff for them to track. I would do a complete search on you PC.