Just to throw another proposition into the mix:
I was in a similar position a couple of weeks ago.
I had a significant amount of Canon kit (lenses, remote release cable) that
was collecting dust, and was trying to decide bewteen the 300D and the Nikon
D70.
The initially obvious choice was to go for the Canon as then I could use all
my stuff with it. However, after further research and talking to my
photographer friends, I decided ultimately to go with the Nikon, get new kit
to go along with it and sell the Canon bits.
I don't want to start a war regarding the merits of the 300D vs the D70, as
this has been done many times, but just read the overall conclusion from
dpreview.com (probably the most respected online reviewer of digital
cameras) on this page:
http://www.dpreview.com/reviews/nikond70/page27.asp
This basic implication is almost unanimous among the various review sites I
read while researching my purchase.
Both cameras are undoubtedly excellent, but if your budget isn't tight, you
don't have a strong loyalty to the Canon brand and you can stomach the idea
of replacing all your Canon bits, I'd say that the Nikon pips it in this
segment of the market.
Rudi