I have set my linux (Mandrake 9.2) screen resolution to 1152x864.
WinXP also runs in the same machine with the same resolution. However,
my desktop in linux is larger (larger windows, fonts, etc). If I change the
linux resolution to higher than it is, then I will have to resize the screen.
If I do so then I will have to change the resolution in XP too, and so on.

What should I do?

My previous SuSe 8.2 had a tool that streched the desktop to fill the whole
screen.