How can I have my desktop computer communicate with my GPS?

My computer is a Dell Dimension 8200 running windows XP version 5.1 with SP 1.

My GPS is a Garmin eTrex Vista that needs to connect to the desktop to upload & download information from MapSource (v 4.07) software via a serial cable. I set the software to use Com 1 at 115200 baud but it skips Com 1 and tries to connect using Com 3, then gives the following message:
"Unable to find a GPS
1. Make sure GPS is connected (it is)
2. Make sure GPS is turned on (it is)
3. Make sure GPS interface is set correctly (it is)."

I called Garmin & they said another program is conflicting with the GPS. I tried turning off my PDA's hot synch software but the error persists.

Any suggestions on how to solve this problem?

Can you set the GPS software to a different COM port?

Can you tell from the Device Manager what is using COM1?

If so, perhaps you can remove that device via the Device Manager, physically remove the device, then reboot, thus allowing the GPS to utilize COM1.

Then reinstall the physically removed device, reboot, and the system should then choose another COM port for this hardwares usage.