I've heard some people are having good experiences with Windows 7 build 7000 on their Samsung Q1 UMPC. Now, since my device has a really slow processor, I wonder if those individuals are using a different device that has a faster processor.
800 MHz just isn't fast enough to run either Vista or Windows 7. Plus, when the processor clocks down to 600 MHz, it's even worse. The Q1 Ultra Premium runs a Intel Core Solo 1.33 MHz processor. However, it's also a thicker device.
So, are you willing to sacrifice weight and size for performance? You can be like me and just continue running XP Tablet. It runs fine on my device and works for me.