Would this be worth jumping ship over? (Meaning ditching the D40X and purchasing the 450D instead). I haven't invested in any Nikkor lenses yet so.. ;p

Getting used to playing with the D40X atm tho.

Yeah I heard that the D40X can only use certain lenses because of this missing motor (else have to manual focus). What's up with this anyway?

In comparison, the Canon 450D is able to use all Canon ranges of lenses I presume?

Also, how does this Live View work compared to the PnS? Is there any difference or would this camera be the perfect transition camera for PnS users?

Canon 450D members seem to be growing by leaps and bounds...

Well since your brand is already specified, you might as well go for the 450D or 400D depending on your budget and the features you're looking for.

Aiyo why la regret... DSLR camera you will never regret after taking some photos. Even in automode the photos are of better quality. Your friend regret cause she cannot put camera inside her handbag or dunno how to use? If she needs lessons there are many sifus here willing to give free photography lessons + special bonus free photoshoot for females.

17-85mm f4/f5.6 is in the similar category as the kitlens. Kit lens has IS which would help if you have shaky hands and low light shots. 17-85 has better reach over the kit lens. But in terms of Image Quality (IQ) the Tamron would win. Low light the Tamron would win too.

Do note that if you buy the Tamron you'll essentially be "replacing" the kitlens with a better lens but with roughly the same range.

Not sure about the Canon mount but the Nikon mount equivalent of the Tammy 17-50mm is only 1.3K+. The price shouldn't be that much of a difference.

But yes I would say that the Tammy is the better lens for a direct replacement.