The warranty issue involves a lot of judgement calls by techs. Hardware should be covered irregardless of the OS installed, but some "hard-a**es" will use it as an excuse - while those with a kinder heart will be understanding and will repair things.
The EULA's state these things, but it takes lawyers to figure them out.
Drivers are available for most hardware on computers today - but they are getting more and more difficult to find. The reason for this is newly developed hardware won't necessarily have XP drivers developed - but older hardware usually has an XP driver somewhere on the web. I've used HP drivers in Dell's (for example) to fix this sort of issue.
Hardware drivers are fairly easy. You get the hardware ID from Device Manager, then search http://www.pcidatabase.com
for the Vendor ID and the Device ID numbers (USB devices are at a different page...search for USB Device ID in Google).
Once you know the manufacturer and model number of the device, then you can search the web for XP drivers. This is sometimes a long and painful process - but eventually you'll locate all the hardware drivers.
Now, the "common" module for the Toshiba's is a different matter because (if I understand you correctly) that "device" doesn't show up in Device Manager. So, the thing to do in this case would be to research the Toshiba models that used this feature back when XP was being sold - and then try that application on your XP system.