Seen this on a Dell - No idea if it will work on a tosh!!!
Do you have a key labeled FONT? On the dell's it's the F7 key.
If you do, Hold down the FUNC and the FONT key, The desktop should expand and fill the whole screen.
The other thing to look at is the resolution - What are you running in?
Most laptops will handle 800 x 600 or even 1024 x 768, You may have 640x480 which the laptop has shrunk down to pretty the fonts from becoming "jagged" looking.
Gary.