Well personally I don't like the handling of the 1000D, it just feels too plasticy and it is relatively slow. The 450D is a very capable camera (head and shoulders above the 1000D), it has a faster frame rate and bigger buffer (more useful for action than landscape). For me though the 40D is better than both, the feel in the hand, and better high ISO performance would make it my choice. I think that the 40D is one of the best DLSRs that Canon have made.
Whichever way you go budget for the other bits you'll need/want. Spare batteries, memory cards, camera bag and a decent tripod (essential for HDR and startrails).
|