so maybe cats are okay. From what I've gathered, Muslims don't care for rats. Since cats eat rats, maybe cats are okay. I even saw a story that claims Mohammed cut off the sleeve of a coat to prevent waking his cat. That might explain his opinion of dogs.

There was also this:

The Prophet(s) told his companions of a woman who would be sent to Hell for having locked up a cat; not feeding it, nor even releasing it so that it could feed herself." (Narrated by Abdullah bin 'Omar. Bukhari, 4:337; recorded in Riyad (Ref. No. 28), Hadith No. 1605; p. 271. Also Muslim, Vol. 4, Hadith No. 2242. English translation by Abdul Hamid Siddiqi; Sh. Muhammad Ashraf, Lahore, Pakistan; 1976; Vol. 4, Hadith No. 5570; p. 1215. (According to the English translation, this Hadith was also narrated by the Abu Huraira and by Naqi who had heard it from Abdullah); Hadith No. 5573; p. 1215.) This Hadith has been recorded by almost all the authentic books of hadith, as the Re. No. 53 will show)

I did see some bad references to black cats, though, along with black dogs and black snakes.