Thanks for your responses!  It looks like I will have no problem using Windows 8.1 with my UBS GS-911.  Very good.
But…what is a "stable?"  From Haakon's response, I have to assume it is the regular non-beta program, as in Version 1303.3, right?  There must be "stables," and Betas?  I did not erase 1303.3 when I downloaded the latest Beta, which I understand will only work for a few months.  When will there be a regular non-beta program to replace 1303.3 and how will we know it is available?  I check the regular web site occasionally, so I guess that will be it.
Thanks!