To obtain the System ID for your Palm OS or Windows Mobile handheld / smartphone, you must first install the demo version of Pleco 2.0. The demo version uses the exact same application / data files as the paid version, you convert it to the paid version by installing a small "keyfile" which we send you after you place your order, so you won't need to install the software twice. If you run into any problems with installation, we're perfectly happy to provide technical support even if you haven't bought the software yet - just contact us and we'll be glad to help.
On Windows Mobile, you can download the demo version from this page, and installation instructions are available here.
On Palm OS, you can download the demo version from this page, and installation instructions are available here. (the screenshots on this page are taken from the Windows Mobile version, but they look pretty much identical on Palm)
Once you've installed the software, simply launch it and you should be immediately presented with this screen:

You can copy down your System ID from here (where the XXXXXes are in the screenshot).
Alternatively, after opening Pleco 2.0 you can get this ID by going into the Ordering screen. To get to that screen on Windows Mobile, tap on the "Dict" menu at the bottom left corner of the screen and choose Ordering; to get to it on Palm OS, tap on the menu button at the top right corner of the screen and choose "Ordering" from the "About" menu. That will bring you to this screen:

You can copy down that same System ID from here.
Alternatively, tap on the "Card ID" button to get a different ID code that's tied to your handheld's SD Card; you can enter that on the order form instead of a System ID to get a keyfile that will work on any handheld with that card inserted, so that you won't need to request a new keyfile when you change handhelds as long as you keep the same card. This does not affect where Pleco's data files can be stored; you can use a regular System ID but still store those files on an SD card, the software doesn't care.