Haven't tried to capture in *.jpg file format but do capture
*.bmp file format, frequently.
GetPDAScreen a freebie at
www.newmad.se/software.asp says it'll
capture in *.jpg image format.
At any rate, save in any format to your desktop.
Open the *.bmp (if that's what you saved) in any editor, i.e.: MS Paint, and then
"Save As" from the drop down menu. *.jpg is one of your
options, click on it and save. Presto, the screen shot is a *.jpg file. Delete the
duplicate *.bmp file to save space on your hard drive.
In MS Paint you can also change to 100 x 100, save the image,
and you can upload for Avatar.
ColorPicker at the same url above is another very decent and
also free, PDA program. Change colors on your Today screens.