Hi Pete,
I haven't used this device myself, but there are now Windows 7 drivers (both 32 bit and 64 bit) available for download from Yamaha at the following link, so it should be OK ...
UX16 - Yamaha Downloads Other European Countries
If you decide to go for it, please post back with the outcome. I'm sure that this information will be useful for anyone else considering it.
Regards
Ian