I speak Canonese.
The 28-200 should be compatible with your newer Rebel only way to find out is to mount it. Some older Sigma EF lenses are not compatible with the newer Canon DSLR's. The 28-200 is a decent lens for what it is, but if you want a good walk-around does-it-all lens, look into the Tamron 18-270 Di-II LD VC, or if you want to share this lens with your 35mm Rebel, the 28-300 Di.
Excellent image quality, has aspherical elements, minimal chromatic abberations, AF is decent and the VC (Vibration compensation) is ridiculously effective, I have hand-held sunset shots @ 1/5th second and got a clear image. I have more problems with my models holding still than camera shake in low light.
Also, get the Canon Nifty Fifty (50mm f1.8) try to find the old version with a metal lens mount, it has better optics than the more expensive 50mm f1.4 and usually trades on the street for higher than the newer 50mm f1.8 II with a plastic mount, which I own. It's a good lens but if you can get a good deal on the early version with a metal mount you got a keeper.
The 28-70 f3.5-4.5 macro is a great lens. The 70-210 f4, of vintage days in EF flavor is a decent lens as well, and the good ol' 75-300 f4-5.6, try to find the earlier Japanese-made model it supposedly has better optics.
If your T1i came with the Image Stabilized version of the 18-55mm kit lens, keep it, much better optics than the older non-IS 18-55. The 28-135 IS is a good walkaround lens as well, but they trade for anywhere from 250-400 dollars.
If you got deep pockets, anything with a red L on the end of it will work great.