thank you for the information.
None of us has vista. The screenshot looks a bit odd. Just as vista has locked the resolution of the screen. Could you test if fiddling with the parameter
fullresolution does anything for you (for example try regular screen resolutions like 1024x768)
You can find this option inside dosbox.conf (see the dosbox menu entry)
you may need to combine this with the output=surface setting
(setting it to overlay or ddraw for example)
I'm just curious if there is a combination that produces better results.