I had a 2.7GB HD that weighed about 15 lbs.
I put the super-tower case it was in out by the street when packing to move, complete with Asus P2T4 and K6/166 jumpered for 225.
It sat there for about a week and a half before anyone took it, while someone wanted my old mattress they saw lying in the snow within minutes.
My old K6-III 400/475 tower with 6x4 CD changer, CDRW, DVD Reader, 2 hard drives, NIC, TNT, Voodoo, SB AWE 32, 56K Supra, and 7 cooling fans weighs quite a bit, probably about 50-60 lbs.