If you are talking to me, i've never actually tried to quantify my collection, but i'll give you a loose estimate of portions of what i have and this is what i have immediate access to, because part of my collection is in storage (garage, attic) that i would have to make an effort to get to. Most of that stuff is on media i no longer use on a regular basis i.e zip disks, vhs tapes, 1-8 speed cd-r's, etc.
Currently, I transfer everything from my hard drive to cd-r, i've started using my dvd recorder alot more, but mainly for things that won't fit on a single cd-r. I buy cd-r's in spindles of 100. A cd-r is 650-700 mb (1/2 gig for easy computation). That would be 50 gigs per spindle.
Let's start with video/movies. I have 3 spindles containing short clips, which i no longer bother to download cause i only collect full length videos now. That's 150 gigs of short clips. I have nearly 1000 dvd's movies, not including the 500-600 movies i have on vhs tapes.
As far as pictures. I started collecting pics when you used to have to manually encode and decode them from Bulletin Boards. Also i was a member of many websites for years and have the entire contents of those sites. For example I have 22 cd-r's of content from Digital Dream Girls, which i was a member of for 2 years. Over 100 from 1 By Day, 36 from Danni's HotBox, etc, etc. 14 spindles of pics in my immediate vicinity, about 700 gigs of pics.
I haven't even mentioned the two 80 gig hard drives in my computer, 160 gig external hard drive or the 4.7 gig dvd discs that i am using now.
I've been collecting on and off since the mid 80's. Shit accumulates!