Didn't Windows Update come up with anything in the optional section?
What is the exact model number? When I go to Toshiba's support page, it lists several "satellite m45" models, e.g. m45-s161, m45-s1651, etc. With this information, you could
- check if there's Windows 7 driver there
- check if it has Vista/XP driver, if yes, then try run them in compatibility mode
- check the specifications page to see, what is the exact model of the video card. With some luck, you could find a suitable driver for it on AMD's or NVidia's site.