*Update: Download ATI Radeon X300 driver for Windows 7: http://www.4shared.com/file/199253812/27d26aeb/atix300driver.html
I attached a link which contains the back-up of the driver for ATI Radeon X300 for Windows 7. Since I'm no longer using Windows 7, I can't tell you for sure if it works or not (it should be working). I think it might be installed via control panel, by clicking update drivers (and selecting the file you've downloaded). Note that you should have WinRAR, because it's a .rar file (uncompress it before starting the update procedure). Please leave a comment to know if works or not !
As you probably know, the are some problems on running aero effects from Windows Vista or 7 on ATI Radeon X300 graphic cards, due to incompatible drivers with these operating systems. After searching for hours on forums, I thought there is no change of running aero from Windows 7 on my Dell D610 laptop. But I found a solution, when I was searching a driver for my sound card.
There is a program available, named DriverMax, which searches automatically for newer drivers available for all your components inside your computer. In the free version, you can download only 2 updates for any pc component every day, in the paid version the number being unlimited. Until now, it did his job excellent on all my computers, even if they were running Windows XP, Vista or 7.
So, just give it a try, it takes you nothing: http://www.innovative-sol.com/drivermax/