vocal music for a newbie


I've never listened to any classical music with vocals until getting into Beethoven's 9th symphony recently. I want to start hearing more but have NO idea where to begin. can you folks give me some specific recommendations based on my loving the 9th? (although I would be happy to "stretch" also.) please, what are the essential performances that should be heard?
tagyerit
I have been enjoying the works of Chanticleer, an a cappella ensemble released on Teldec. There are many recordings to choose from. My personal favorite is Palestrina: Missa pro defunctis - Motets. If your system has good imaging this recording will show it off!
excuse 2d post, my brain was in so-mo above. the choral piece that stands highest in my collection and regard is Faure's Requiem as performed by Herreweghe w/a chamber orchestra recorded by Harmonia mundi #9011771. This is without any doubt one of the most beautiful, intimate, requiems i have ever heard (except for an earlier herreweghe performance of the original version which is much smaller scale and in my opinion even more beautiful because of the scale. also on harmonia mundi 901292). in the latest edition you also get an excellent performance of Frank's symphony in d minor.
this is great, thanks folks. i'm off and running! I had not even heard of Faure, or the group Chanticleer; and Strauss would never had occured to me. I will seek them out.
so far based on the good advise of Aida_w my life has been changed by the B minor Mass. unbelievable! this stuff is just so beautiful...