Oh, well, 10.2.8 is your problem. I'm pretty sure WPA support didn't turn up in OS X until 10.3.(something?). Upgrade the eMac and you should be fine under OS X. You're still SOL under 9 unless you use a standalone wireless bridge or something.
(I wouldn't worry about someone "driving by" and hacking into a TKIP WPA network. The attacks against it are *obscure*, require deliberate hacking, and mostly amount to DoS attacks or *very limited* spying on data sent to an active client. Unless they guess your password they can't join the network. WEP of course is practically useless.)
The "soft firmware" trick is something built into the "oronoco" linux driver:
http://wiki.debian.org/orinoco
I don't know of it being implemented on any other OS, unfortunately. If you hunt hard enough you *should* be able to find the flash files to convert a Silver to a Gold, but I seem to vaguely recall there being some compatibility issues with the OS 9 drivers depending on what specific firmware build you upgrade to. :^/