>I haven't been able to install the tablet driver,
>because it tells me that COM1 is not available.

Do you have the tablet connected? If so it sounds like XP thinks it is a 
mouse, as it has probably sent a data string to the port when powered up, 
which XP detects and figures a mouse is present.

Because it is a tablet it may also be deliberately trying to look like 
aerial mouse, so it works without the driver. 

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