How do I look for a good keyboard?

I have an old Casio keyboard with 76 keys and rather poor quality and unrealistic synthetic sounds. I don't do much on stage, but I do a lot of playing in the studio, however I'm not personally a good technician. If I'm looking for a keyboard with all around good piano, synthesizer and instrument sounds, how would I go about searching for that kind of thing? Are there any "tech specs" that I should know about?