I didn't want a large HD - I wanted a fast one. Try finding a 7200 RPM or 5400 RPM 4Gb harddrive. The smallest they make now is 40 Gb, so that's what I got. Everything I've got - including 1Gb of digital music - fits in 4Gb.
If I switch to Compact Flash, I'll just get a couple 4Gb ones. (but by that time, the minimum might be 40Gb ;-) )