There's tons of videos out there for taking apart the new Alu imacs but not many for the older polycarbonate imacs.

About 12 months ago I posted on here a take apart guide for the 20inch c2d imac's, sadly it got lost when .mac became mobileme. I've recently completed a video this time of a hard drive replacement.

Let me know your thoughts...

YouTube - Intel imac hard drive upgrade from Burtonbytes