Hi, welcome to TSF
If this is a replacement card rather than a new build, did you uninstall the previous driver before upgrading?
Are you using Vista 32 or 64?
Catalyst 7.10 for HD2600XT/Vista32
Catalyst 7.10 for HD2600XT/Vista64
To avoid conflicts, you need to remove the driver you already have installed. Go to Start > Control Panel > System > Hardware tab > Device Manager button. Click the [+] next to Display Adapter, right-click the ATI Radeon entry and select Uninstall. Reboot into VGA mode (keep tapping F8 for the Advanced Options menu). Disable your antivirus to avoid conflicts. Install the new driver and reboot to complete.