mozart is good too, but i can't recommend anything as such, cuz the titles of his doesn't really say anything about the music, except for the operas and some of the symphonies, which has a real title... i have all Mozart's music, btw

Complete Works spread across 170 cd's
i want some Wagner too someday.. and some more stuff.
Vivaldi - Four seasons is always a winner, everybody knows that.
The problem with buying classic music is there are always many different ppl who have interpretted the same piece of art, so there's many versions of the same music. Some good, while other is crap and sloppy.
Here's an exellent classic review page:
http://www.classicstoday.com/
I myself have three versions of Vivaldi's - four seasons, and while one of them was somewhat crappy, the other one got a full score on the above mentioned page, which i got fairly cheap on amazon as with the crappy version.. however, the best version i have, i downloaded for free, performed by students or something like that..