AMD Game Forums - Drivers no longer listed on Windows Updates?
They posted a x300 driver for windows 7 and the reason you are having trouble finding a driver.
EDIT: The link to the driver on that post is now dead, here is a complete article on the x300/Windows 7 issue along with a driver.
I cannot insure that the driver is legit or any of that other legal mumbo jumbo.
The IT enthusiast
Double EDIT: I blindly assumed you have the Radeon mobility x300 option due to your inability to get a working driver, verify you do have Radeon graphics before reading any of the information I provided.
The only other option is Intel 900 which I would assume Windows 7 would have picked up on.