I would highly recommend you keep your original CF card around so you can try out the Zonbu update, but I’ve had a number of people ask about how to install XP on a new CF card.
Some people have suggested different sizes/speeds matter. I had no problem using a 133x 8GB card. I wouldn’t recommend anything smaller than 4GB.
Partition and format the card for FAT32 in a desktop PC using a card reader. Plug a USB CDROM in to the front of the unit and follow the prompts.
Originally I tried to use an XP install a friend loaned me, and it didn’t work. It wasn’t an official release. I used my official XP disc and it worked just fine, just a heads up.
So just make sure the (new) card is formatted for FAT32 and has one partition and then boot from the CD and you should be fine. I warn you now, its very slow. It is NOT a replacement for the Zonbu as a usable desktop, but you can use the Zonbu hardware as an appliance. A friend of mine is using his just to update his public IP so he can access his NAS when he travels. You’ll also need to hunt around for windows XP drivers for your sound and video. I can post later on where I found those if you’re interested.
If you want to surf the web and continute to do the things you enjoy on the Zonbu, you need the Zonbu OS, no questions.