LPs and CDs stay in balance, currently around 1100 of each, plus about 450 7" singles and a half-dozen 78s (who could resist mint Sister Rosetta Tharpe shellac at Goodwill?) I haven't gone far down the DVD road yet, only a half-dozen of those as yet.
My first LP was Styx's "Kilroy Was Here," and I don't have it any more, nor do I have Bauhaus's "Burning on the Inside," which I'm pretty sure was the first CD I bought - yeech! I bought all of the Minutemen's "Post-Mersh" CDs and Bongwater's "Double Bummer" on my birthday a few months later, maybe my 10th-13th CDs, and I still have those. The first LP I bought that I still have is The Cramps' "Bad Music For Bad People," and the first single was The Dead Kennedys "Nazi Punks F*** Off." The best boxes of all for CDs, if you can get your hands on them, are the boxes that Quantum DLT tapes come in - they're for high-end computer backup devices, and come in incredibly strong boxes that hold about 120 CDs. Assuming you don't have the necessary connections, there's a largish LP mailer that Bags Unlimited sells that's quite stout and holds maybe 50 CDs. If you have a CD store nearby, see if you can get the 25-count CD boxes that CDs come in, tape those shut and pack them inside larger boxes. The main thing is really getting a sturdy box, taping it up tightly, and packing it tightly so the CDs do not bounce around. -Chris