I agree with Peter, a new camera would not make you a better photographer. The only way to improve your photography is to go 'out' and take photos, read some books, explore and experiment. And of course, Barry and Peter, please join the weekend contest. The more the merrier
There are only two reasons why I would ever recommend spending your hard earned money to get a 'better' camera. The word 'better' being subjective here.
First reason: you have become very serious about photography (doesn't matter whether you making a living off it or not) and your current camera has too many limitations
Second reason: your current camera has suffered 'damage' beyond repair and it's already several generations old
Now, do keep in mind that there are several good cameras available in the second-hand market. If you do feel that the 20D you has become too old and you're not sure about buying a brand new model, look in the second-hand market for cameras like the 450D, 500D, etc or even advanced compacts. Just be sure to buy from a reliable dealer when purchasing second hand items.
Having several cameras and dozens of lenses does not make you a better photographer, it just makes you poorer (talking from first hand experience here). What makes anyone a better photographer (whether they own a camera phone, a compact, an old polaroid, or even an expensive DSLR) is knowing how to use their camera, which is just a tool for artistic creativity, well.
Normally when people post questions such as "should I get this camera or that camera" I just give them a comparison and get them to think "do I need these features? do I want to invest my money into this item" etc.