This problem (or a 2 similar ones) nagged me for a while. We run a clipper application on a network with XP workstations. I wanted to run the application in full screen mode, and even though I would change the layout settings to 80x25 and full screen, I'd get a full screen (i.e. not a window) but with my stuff scrunched on the top half of the screen. I'm not sure why what I've done works, but here is what works for me:
For the cmd.exe, command.exe, (myprogram).exe, and/or any included batch files, I change their properties as follows. As expected under the options tap I select Full Screen. I don't think this part matters, but under the Font tap I select TT Lucida. Under the Layout Tab I do a few things. As expected I change the Layout to 80x25. Then I uncheck the "Let system position window" box so I can edit the windows position numbers. I then change both the settings (Left and Top) to -4. Then I recheck the "Let system position window" box.
This all worked great for me until I would print from the application, then I'd have to restart the application to fix the screen. The workaround for that is to stop sending print files to an LPT port and instead use the xp print command as follows:
torun="C:\I386\PRINT /D:\\NETWORKNAME\NAMEOFPRINTER "+ MYFILETOPRINT
Since I implemented these changes I have not had the half-size/full screen problem.