Padraigr, I would like to apologize on behalf of my compadres here for completely taking your thread in a total different direction.
Guys, this person is contemplating a purchase, and I think this heated debate of the FF issue (in which I am a common participant) should be held elsewhere.
Padraigr, there was a link on the previous page to Snapsort.com:
Compare the Nikon D5000 vs Pentax K-r
Snapsort is a great resource when comparing cameras. But it's really just a surface comparison, and you really have to look a bit deeper. For instance, the D5000 gets a plus for better low noise/high ISO, but it only goes to ISO6400, so that's somewhat irrelevant.
As has been stated, when you purchase a DSLR, you're committing to a system. The system as a whole needs to be evaluated as part of the decision. Pentax has wonderful, lovely prime lenses, but they're not cheap. Nikon has some fairly inexpensive fast primes for low-light, but they're not stabilized, which you generally need in low light. Nikon has a better flash system. Pentax has built-in SR, and the Pentax Limited primes are some of the best lenses ever. If you're amenable to manually focusing, there are treasure troves of old K-mount lenses at garage sales and flea markets. I think Pentax gets the nod in ergonomics, the Nikons just don't match my hands well.
Now, the K-r has a known issue with focus accuracy in tungsten light (indoors). It has been beaten to death and is brought up at every corner. I have the K-r. It does front focus in tungsten light. What that means is that the thing you're trying to focus on is a little out of focus because the camera is actually focusing a little in front of that point. But for all the other features of the K-r that I love, i can live with and deal with this issue. Other cameras have the same problem.
I hope your questions get answered and you end up with the camera that fits you best.
Edit: Sorry, dragra, didn't see your apology in the previous post...