(0xc0000135) means the application you are launching failed to initialize properly...
What exact ATI driver are you installing? Are you running Windows XP with SP2 and all the latest windows updated including Microsoft .NET?
ATI CATALYST 7.8 drivers should work on the Radeon 9550 video card and can be downloaded here:
http://ati.amd.com/support/drivers/xp/radeonx-xp.html
ATI CATALYST Driver Installation Guide:
Installing the .NET Framework
The CATALYST Control Center requires Microsoft .NET Framework prior to installation. The CATALYST Control Center is an application that allows you to control the configuration of your ATI product. You can verify that you have the .NET Framework by checking in the Add/Remove Programs list in the Control Panel. If the .NET Framework is not listed, please download, and install it before proceeding. Microsoft .NET Framework
Installing the Catalyst Software Suite
The Catalyst Software Suite contains the Display Drivers, WDM drivers, and the Catalyst Control Center. Once the file is downloaded, please follow the directions below.
1. Double-click on the downloaded driver file. Windows XP Service Pack 2 users will see this dialog box. Click Run to start the install process.
Use the default directory for extracting the files and press the Install button.
At this point the driver will start the extracting process before the actual system install begins.
2. Click Next on the first install screen.
3. Click Yes to the License agreement.
4. Click the Express button.
The installer will start to load the display driver first.
Next you will see the WDM Capture drivers load (for VIVO or All-In-Wonder).
The Catalyst Control Center setup will start shortly after.
A dialog box will indicate the install progress.
5. Click Finish to restart your computer.
This concludes the installation of the display driver.