Canon has changed their lens mount two times (well, three sorta) in the past 40+ years. In the early 60s, they changed from their R-mount to FL. By the early 70s, they had developed their FD mount, which was backward compatible with the FL mount (that's the "sorta" mount change). In the late 80s, they introduced the EF mount and haven't changed it since, and honestly I don't know why they would. At the time the EOS EF mount was the most technically advanced mount in existence, and to this day remains superior to all others --- IMHO. Okay, okay, so there's the EF-S mount now, for the crop-body cameras, but it's still the same EF mount, it's just the EF-S lenses are designed not to mount on non-crop-body cameras (the rear elements protrude inward too far and would hit a full-frame camera's mirror).
Jcooper, the good news is there are a lot of EOS 35mm cameras out there that will fill your needs. I would recommend one of the Elan models, like the Elan II, IIe, or 7. Here's an Elan II on
eBay for reasonable:
Canon EOS ELAN II AF 35mm Camera Film EF - eBay (item 130331994415 end time Oct-18-09 17:31:16 PDT)
You didn't mention specifically which lenses you own. MusicaleCA brings up a good point. For any EOS 35mm camera you may buy, you'll need regular EF lenses for it. I'm guessing by "standard" you're referring to the EF-S 18-55 IS that comes as part of an XS kit. And I'm further guessing that your portrait lens is a "nifty fifty", aka EF 50mm f/1.8? If my guesses are correct, only the 50mm will work on an EOS 35mm. And it won't be considered a portrait focal length for a full-frame camera, either. You'll want something in the 80 to 100 mm focal range for portraits.