I haven't counted in quite awhile, but I have somewhere in the neighborhood of 1200 CDs, about 20 LPs and more tapes than I can count.
Bear in mind that I was in the music business for a number of years and received a lot of music CDs that are promo copies. These aren't unknowns either. I used to service all the printers at Geffen Records, and the IT manager there was a friend of mine that would often hand me freebies on my visits there. Doing session work in different studios always brought more promos and freebies as well. I also purchased CDs a lot in those days.
I have only ripped a small part of my collection to my hard drive as MP3s, for my own personal use. I was going to rip every CD that my wife and I own at one time, but that was going to take forever, so I just took stuff as the mood hit. For MP3s, I have about 5,000 songs now, over 30 Gig of them.