Ok, here we go:
1. Check what OS you are using - if it is Windows 95 - that could be the source of the trouble - it doesn't officially support USB. Windows 98 is better, but still troublesome with certain hardware.
2. You said you have 2 USB ports on the PC and more on a card, correct? The ports on the PC (motherboard) will be USB 1.1 - USB 2.0 didn't even exist when the system was manufactured! Your add-in card is probably 1.1 unless it was just installed within the last several months. The error message you're getting is probably related to the fact that the scanner is USB 2.0 - it will not work on a 1.1 port, however 1.1 devices will work on a 2.0 port.
3. Check the "USB Serial Controllers" in your device manager - if there is a yellow question mark next to it, it means there is a problem and the drivers need to be reinstalled/updated.
4. As far as the power issue - if a device needs additional power to work properly, it will include an a/c adapter. Webcams are low power and will run off the USB port just fine.
5. To find info on your OS and CPU speed, right-click on "My Computer" and select properties. It will bring up the System Properties dialog box - the first tab will show your OS and type/speed of CPU. To get to the Device Manager, simply select the "hardware" tab and you should see the device manager.
6. See if you can download webcam drivers from the manufacturers website - you may just need new drivers to get it working properly.
Good Luck! Hope this info helps.
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