According to this
your laptop will support Win7. Just go to the drivers/downloads section of Toshiba.com and mske sure they've got Windwos 7 drivers for download.
EDIT: depending on the age of the laptop Toshiba may give you another install disk from anywhere from free to $30.00, too. So, if it is still under warranty I'd call Toshiba and make up some junk like the install disks came corrupted. A little mischievous, but it has worked for me before.