the 1000d is a a good camera but limited in what it can do. remember as u become more experienced in photography the bug bites and then u realize that the entry level camera was a waste of money.the only problem with the 1000d is that it is too slow[shutter speed i think is max 4 frames a second]so getting expensive glass would be a waste on that body. if u have the budget go for a pro body which will give u those 10 to 15 frames a second and make the lens worth it.tamron and sigma do make good glass but personally i would stick with the same brand as the camera.i do bird photography and specialize in birds in action which forces me to use a pro setup but it is worth it as i am not limited if i want to do other genres.