I’m not sure if you are worrying about Vista just yet, seeing that it is still in beta, but I thought I would give you a heads up about a possible problem in the last three versions 5.6.10,11, and 12.
The tray icon for temprature is appearing garbled and unreadable no matter what font, size or weather or not transparent is checked.
Interestingly, I was randomly picking foreground and background colors to see what happened(something I have done in all three versions I have tried on vista) and I have run up on a few forground colors that are working in the latest version(12) (white(255,255,255) and green(0,255,0) are the clearest I can find) but the background color seems to make no difference at all as if it were stuck in transparent mode.
For example a white foreground on a white background still shows up in the tray icon as white text on a transparent background weather the transparency checkbox is checked or not.
This does seem to be a problem with the new Areo interface it seems to work normally when Areo is turned off.