There is a Roland forum where they claim to have developed of a driver for the XV-5050 for Win 7/64. It can be found under:

www.rolandforums.co.uk/forums/viewthread/1319/

I am still waiting to receive mine, but hope to get it soon.
Hope this can help others too!

Tonnie

PS. Should anyone come across a driver for Win 7/64 for the SC-8020 I would be very interested!