I'm laughing at some of the answers... he he....
OK, the fact is that the lenses will work the the digital version. If you have quite a few lenses then that alone is good enough reason to stick with Canon as these are the most expensive part of a photographers bag (normally!).
The 350D (Rebel) is a fairly good camera considering it's cost.
As for not choosing Canon is you want go pro.. what a load of bull. About 90% of sports photographers use Canon! LOL.
The lenses will provide some magnification though. Since the sensor is physically smaller than a 35mm frame the effective increase in lens length will be 1.6x longer. For example a 50mm lens will effectively become an 80mm lens. This is good for the telephoto end of the range, but wide angle becomes quite expensive.
If you really did want to move away from Canon though, I would suggest a Nikon. The D70 and D200 are very good cameras.
I personally have a Canon 20D (same sensor and processor as the 350D), and a 1Ds II. Both are excellent cameras. The 20D is excellent for sports and fast moving subjects, and the 1Ds is fantastic for fashion or portraiture.