With all due respect to PocketBrain, I don't think that's quite correct. He is right that only the x50v and x51v support direct VGA-out (although a cable accessory is a necessary first purchase). The output resolution however can be higher than 640x480.
For instance, on my x50v, ClearVue suite can display through the cable at 1024x768 (which I have verified). I also think (although I do not know 100%) that products like
http://www.nyditot.com/NVDPage.asp can allow for all programs to display at resolutions beyond 640x480.
Without any additional software, you are limited to a true "mirror" of the Axim screen, which is 640x480, though.