Sorry, but are you talking about the 40D or the 400D (aka digital rebel)?
The 40D will be difficult to upgrade for a rather long time.
The 400D is also very good, and handier to manipulate I guess.

As for the noise: that is as good a certain much lower. And autofocus on the 40D is quite fast and rather accurate. I haven't got any hot pixels on mine but with the soft that comes with it you can locate these and have them cured automatically.

Did you read the reviews on dpreview (I always jjump first to pros and cons). Both the 400D and the 40D are highly recommended.

There are no Borg. All resistance is fertile.