Pretty much. The Axim X5 has both CF and SD slots. I use an SD card for data transfer mostly because my laptop has an SD slot built-into it.
External card readers often support multiple flash cards so you could potentially use either CF or SD depending on your preference. These connect via USB.
What you need to watch out for is that the Internet cafe may not want you plugging things into their computers. Also depending on which operating system they are running, they may need a driver to be able to use the card reader, and if they do need a driver, the operating system may be "locked down" so that you are not able to install it.