[Russ Smith]

As others have said, either will work just fine, but here are a few things to consider:

There aren't a lot of SD options other than memory. The hx4700 supports SDIO so you could use a GPS unit, but you'll probably be using it for storage. There are many more options that come in CF format.

On the other hand, CF cards can come in considerably higher capacities. Currently the SD slot doesn't support SDHC cards, so the upper limit is 4GB. You can, however, get a 16GB CF card that will work in the CF slot.

What I do is use a 4GB SD card for installing applications and some data. It's pretty much always in the machine. I use the CF slot, along with some adapter cards to read xD Picture cards and Memory Sticks. I also have an 8GB CF card with my entertainment files (videos, e-books, etc.) I have a CF modem and a CF wired Ethernet card as well, but I hardly ever use them any more.