Yeah, what Andy said. The speed different is fairly inconseqential and will depend on the camera more than the card.

Compact flash is the old standard, and SD will be the new one, so you're not going to get burned with either of them. I was tempted to go the CF TO SD adapter route and just buy SD cards, but I got a good deal on a couple CF cards. If you end up with a CF camera, consider buying the adapter and the SD cards. Howerver, if you're going to keep the camera for over a year, your memory card investment is probably going to be inconsequential when it comes to your next camera.

In Rob Galbraith's CF database, check out the Canon 1D(s) Mk II, as they take both SD and CF, so you can see the speed difference. Unless you're shooting sports with an expensive camera, you're probably not going to notice anyways.

Matthew