Note that not all CF cards will work. Most are incompatible with the hard-drive communication that players use, and will be unable to restore your player to life.
There are some brands that are rumored to have fully compatible CF cards (including Transcend), but the most compatible ones (and the only ones I can attest to) are of brand A-Data, model "Speedy". I bought a 16GB one when I wanted to flash a rockboxed iPod Mini, and it worked. But there was no feeling with the iPod, so I took it out and tested it in a few other players. It worked in all of them.
In the end it ended up with a CF-to-1.8"-IDE-adapter inside my Rio Karma, where it resides today.
The Karma is the best music-only player in history, but it has a known problem with weak hard drives (well, the few still in existence do, anyway). Subtract the hard drive, add flash memory, and the result is pure awesomeness.

It's a bit non-intuitive how forces and strengths scale with size, but it's quite illustrative to look at the extremes in the animal kingdom. Drop an ant from an aeroplane and it will probably walk off. Push an elephant down a flight of stairs, and it will end up as elephant stew.

There is also a non-trivial amount of engineering involved in the design!

I've wondered before how hard disks manage to put up with so much abuse (sudden movement, etc.) despite the awseomely small tolerances inside them - head hovering on a nano-wotsit of air and all that. My amazement is even greater in the case of those Microdrives - which in something like a camera get subject to the most violent forces, yet still work. How on earth do they manage to make the physical side of it work? 'Mazing.

PS When I leave a comment, despite adding a "URI", my "Comment by iworm" string does not have a link to my blog. Not exactly important, but I was curious what I was doing wrong. :-/