Having had a Canon eos 300 35mm SLR for several years, I'm now looking to buy a digital SLR. I think I want to stick with a Canon, but having found a few options, am not sure which to go for, so would appreciate some advice.

Option1: 450D with two lenses (18-55 non-IS, 75-300 non-IS) 550

Option 2: 1000D with 18-55 non-IS 360

Option3: 500D with 18-55 IS 570

I like the 450D and the package with two lenses seems good as I would also like to get a telephoto lens, but would I be better off getting the 1000D and spending more on a better quality telephoto lens (I've found a secondhand 55-250 IS for 150). Or if I'm going to spend more on a better camera, would the 500D, which comes with an IS lens and has more pixels/bigger screen etc., be more worth the money?

I'm just an ameteur so don't need amazing quality - I just want something that I can experiment with more. But I do want something that will last as I improve my skills and possibly invest in more lenses.

I'd be really grateful for any advice.