Welcome to the Forum 
What you need for your camera is any of the over lenses that Canon makes. It just has to say either "Eos" or "EF" on it for it to be compatible.
Also,. there are several good companies that make lenses that will work perfectly. Sigma Tokina and Tamron ,. again ,. you just need to be sure to get a lens that is Canon "EOS" or "EF" compatible.
Several Manufacturers make 28-200mm Lenses now., the most recognizable is the Tamron,. (I think it was there Idea) but you can also get one that will fit your "Rebel 2000/Ti" from other companies including Canon and Sigma.
I had the Sigma 28-200mm for some time and looking back at the photos I got with that particular lens I regret trading "up" to a 28-300mm Sigma. To my eyes the 28-200mm took better pictures,. it seemed to get the correct focus more consistantly and faster.
But they may be too specific lenses,..
Check out the Swans in my Galleries,. those pics were taken with the Sigma 28-200mm.
I Assume you are in the US as you mentioned the Rebel model,. you should be able to find the lenses you are looking for at a Ritz or a Wolf Camera store. Don't get lenses at "Best Buy" they seem to have like a 100% mark up on the lenses!
Or try B&h for an online order.