Translating WordPress to other languages

I would like to translate the last version of WordPress to spanish.
At this time, I don’t care about the WP-admin console, but I need the on-website text and dates to be in spanish.
The last version I’ve found in spanish is 2.01, but I’m getting some bugs with that one.
Anyone knows if there’s a sort of straight and not too dificult way to do the transtation ?

Thanks a lot.