If I remember correctly (it's been so long since I've uninstalled), I am pretty sure it will apply the default windows theme on uninstall. If not, you should be able to force this through the display properties -> Themes tab, anyway, since WindowBlinds fortunately doesnt require hacks, as 2of3 mentioned.
Mike
End of milksama's quote
It's been a while since I've unistalled as well since I love the program too much to do without it.
The last time I uninstalled without choosing the default luna, it booted to classic and I could not get it to change back without reinstalling. I've also seen a few threads in the past stating the same from some who have uninstalled the WB6 trial.
Could be that this is fixed but since I was unsure I thought it best to mention it.