Which Palm Zire do you have?
I've a Palm Zire 21, which has 2 MB, so no way Linux would fit on it
. I also happen to have a Palm m515 which has 16 MB memory and it's also very small (though, I love this one
). Check at NetBSD after the processor type for your handheld. It's more likely that NetBSD would run in a Palm then Linux... I guess. NetBSD runs on nearly everything out there