Hi Blick,
There is no Windows 7 driver available for Canon EOS Rebel XT. However, there is Windows Vista driver available on the Cannon Support websites. Try downloading it and installing the same in Windows Vista compatibility mode and check if it helps.
Drivers and Software - EOS Digital SLR Cameras - Digital Rebel XT
Make older programs run in this version of Windows
****Hope this helps. Let us know if you need further assistance.
Thanks and Regards, Santosh Y – Microsoft Support
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