I'm really no pro on this topic, but I think there are a few ways to solve your problem; some expensive, some free.
As has been mentioned already in the video forum, attaching a neck-strap to your 500d and creating tension between you and the camera will help a bit. Your neck creates a support for the camera, reducing shake.
Something like an LCDVF will also achieve a similar result, as your eye will provide stability like it does when looking through any viewfinder. (I really recommend the LCDVF as the magnification it creates is incredibly useful for manual focussing...)
Obviously, a tripod is ideal. But if you need moving shots, you can carry the tripod with the camera attached (a monopod might work slightly better) and again, this achieves balance as it acts as a makeshift steadycam (in fact, if you search online you can find tutorials to make a real home-made steadycam with weights, for around £30).
Apparently, IS lenses will help (I always use primes so I can't verify this).
Alternatively, you can spend hundreds or thousands of pounds on pro equipment (like track dollies/sliders, professional steadycams, shoulder-mount rigs etc) - and these will, of course, usually produce the best results. But the price premium (for most people) is a big factor.
I hope that's vaguely helpful!
