Good reviews are at dcresource.com.
You can also go to dpreview.com.
Generally I found in those reviews, that the Pentax k10D is on par with the Canon 30d in RAW performance.
The K10d got bad marks for its JPEG right out of the box. But no reasonable photographer would buy a feature rich camera like the pentax and use is as is. It can be tweaked a lot.
The Canon kit lenses, as they come with the Rebels, are, as I repeatedly read, garbage. You have to go to the next level of Canon lenses, which will make it expensive.
The Pentax kit lens is good, not the top, but good. Sharp. And you can use all Pentax lenses ever built for 35mm that are cheaply available on the market.
I myself own a Pentax K100d, and I am very happy with it. I have so many possibilities to tweak its performance, and the colors it gives are great.
Actually, there was a review in PC world, where the K100d clearly beat the Nikon D40, and, in color performance, even the Nikon D80.
So, I think the Pentax K10d is the greatest deal on the market today, a camera Pentax wants to get back on track after their not so good (and poorly named) *ist cameras.
The new Pentax generation is great. I like the solid design, quickly accessible menus, great performance. Like with all DSLRs the meter tends to overexpose, but not as much as the lower-end Nikons.
Also - if you go to Ken Rockwell's website kenrockwell.com, he repeatedly complains about the poor feature sets and displays on the Canons. Ken is a Nikon and Canon fan, and you can read all this in his Nikon D40 review.
(Canons have been known for poor ergonomic design and cheap plasticy feel - at least regarding the rebels, which also haven't been updated in a while).
So, check out the cameras, and buy what feels better for you.