I'm thinking about purchasing a k2500 or k2000. I make house or techno music. I'm not sure about all the prefixes after k2000 like k2000xs? I just need some general info on both of them.

I do not have any experience with the K2000. However, I do have experience with the K25 and can safely say it is the best of the best, regardless of what style of music you play. Before I purchased my K25XS, I played, played with and listened to ALL of the comperable synths....none even came close. I repeated this hands-on comparison when I was looking to make another purchase, again I chose a K25(R).
The prefixes only tell you of some bacis features: "X"= 88 keys, "S"= sampling option and "R"= rack. A modle "RS" means that it is the rack version with the sampling option installed.