Not sure where you heard that. PicoScope works great on XP Tablet. I have a wide screen XP Tablet PC I use both PicoScope 5.xx and PicoScope 6.xx with no issues.
There was a time with some versions of PicoScope 6.xx beta that there were problems with the XP Tablet OS but those have been resolved.
THE PicoScope Automotive Authority
In North America