Try the EF-S 55-250 IS lense. You can get it at Circuit City. Its pretty cheap, and pretty decent.
http://photography-on-the.net/forum/showthread.php?t=492427&55+250
i believe there are more on the site. I could not find an archive section, but I am sure there are plenty taken with it.
I own this lens, its a decent lens for its price. its not a full sensor lens, so if your going to migrate to a full sensor DSLR, your going to be selling this lens with your XTI.
The link above, check it out, along with the archive sections (just do a search for the word archive, and you will have 2 pages of shots with specific lens)
If this is your first camera where you buy lenses, and your not sure what focal length your going to want, try renting some lenses. It is ALOT cheaper than buying them and then reselling them because they are not in the focal length you thought you wanted.
I am by no means an expert, and consider myself a low level amateur, but I have learned a few things in the last few months. One of them is the lens does not make the picture, the person shooting does. Another is, do not go out and buy lenses on a whim, it costs a lot of money doing that.
IS is not "the answer" for a moving target. IS is for *your* movements, not the target's. That seems to be a very common misconception. IS is not a replacement for a low F-stop, though it can help a higher F-stop lens in certain situations.
I personally would rent the lens you think you want, and take a few hundred pictures with it. See if its right for you. How are the colors, sharpness, etc?
If so, then you know what you need to save up for. We can help, as in tell you what lenses we have, or what we like, but in the end, its your decision.