You need to right-click the shortcut icon for FM08 and select properties from the pop-up menu.
A box will appear on which there is a textbox with the title Tartget:
In that box overwrite everything with the following text:-
"C

Program Files\Sports Interactive\Football Manager 2008\fm.exe" --small_screen --windowed
This assumes that FM was installed to the C

Program Files\Sports Interactive\Football Manager 2008 directory. If it was installed anywhere else, you need to change the text to match.
Make sure FM isn't running when you do this (although it won't stop you from doing it, you have to start the game again for the change to happen).