The iBook G3 Dual-USB are great machines... if you can find one that doesn't have the dreaded GPU failure. I love my 900MHz iceBook, to be honest. It's really still a fairly capable little thing, suitable for everything from light gaming (Diablo II-era stuff) and DV-editing (but not compression, unless you let it sit for a while...) to moderate internet activities, including YouTube. Just don't expect it to process a filter on a 2048x1024 image in Photoshop in less than ten seconds, or you'll be in for disappointment.
