How do you change com ports in XP...?

I have a Sony Laptop with a broken interenal modem. I am using a card modem. I have upgraded to XP and now cannot for the life of me figure out how to get the internal modem to release the comport it's on. I'be disabled it and so on, but I keep geting the error for the card modem that it hasn't *started*. ANyone have any idea how to disable...really disable and release the comport...an internal modem in a Sony Laptop. Or better yet, how can I get the other modem to see a comport?
Thanks
Doc

 

If you haven't already, you might try this.....Device manager/ports/com port/properties/port settings/advanced/com port number drop down. Dave