I have been given a Canon XT and the only thing I can say that is good about it is that it is almost like dumbproof!
You won't learn too much photography with the Canon as with the Pentax.
First thing, mine has the 18-55mm kit lens (non-IS) and when I try to look for other lenses for it, it is sooo expensive specially the "IS" ones!
Another thing is that you can't just attache any lens to it, you are actually stuck with the EF ot EF-S lenses..mostly made by Canon too!
As compared to my K100DS, I can do anything with it, and the lenses that I buy are all "IS" or "SR" since the shake reduction is in-body and I don't have to ridiculously buy it everytime I have to buy a lens!
I can do macro, I can attach bellows, do anything with my Pentax..which is a good and a bad thing since with the Pentax, I can be creative with all the tools I need at my disposal and pretty affordable (good), the only bad thing about it is I get LBA since the lenses and the accessories or whatever I can think about for it is affordable!
My Canon XT I usually treat like a P&S if I need to shoot fast and no fuss.
I use the Pentax when I want to be creative and precise.
This much I can say 'coz I have both and use both!
I prefer Pentax and would never part with it!