I actually tried that... didn't seem to do anything.
If you click on 125% it really should have enlarged everything a substantial amount. Would have given you a warning that everything might not fit on the screen and so forth. hmm..
If it's just happening in some programs then you can try to adjust the DPI settings on your computer.
Go to screen resolution, then to make text larger or smaller, Then on the left pane click on select custom text size(DPI). Make sure that the use Windows XP (DPI) is selected and see if that works for you.
Also for any of these settings to take place you'll need to log off of your name then log back in.