Yes, the newer Canon 18 - 55 mm is lens that you have found will fit the Rebel XT. Image stabilization will not function with this body.
All EOS AF lenses are compatible with the EOS DSLR series. See the information below from the Canon website.
Evolution of the EOS system
Since the first EOS cameras and EF lenses in 1987, a number of new technologies have been introduced into Canon's EOS system. As new camera and/or lens features have been developed, this has added to the amount of items communicated between body and lens. Canon has been able to do this and maintain practically total compatibility going back to the earliest EOS bodies and lenses. Most importantly, the lens mount and the gold contacts have not changed one bit!
Features introduced since 1987 which have altered the way data is communicated include:
- Predictive AI Servo AF (focus tracking on moving subjects)
- Micro-USMs (extremely small Ultrasonic focusing motors)
- Tilt-shift lenses with Automatic Diaphragm operation
- Multiple-point AF systems, from 3 points up to 45
- Image Stabilization
- E-TTL flash (which relies on instant analysis of a pre-flash)
- Wireless E-TTL flash
Furthermore, as new cameras have been developed, new and faster communication methods have been introduced to give us faster autofocus, more precise light metering, faster shooting speeds (up to 9 fps with autofocus on the EOS-1v, for instance), and of course the new features that digital SLRs bring to the table.
Data communication has accordingly changed over time, and occasionally a new camera will be launched that modifies how data is transmitted between body and lens. For example, when E-TTL was launched with the EOS Elan II camera in 1995, its aperture stop-down communication was altered compared to previous EOS cameras. Again, all Canon-made EF lenses had processors able to accommodate the shift in data transmission, and worked without modification.
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