There may be another way to go, if you could locate a vintage Belkin or other
early 802.11a/b USB1 wireless dongle that was supported by Mac OS X 10.3.9
or 10.4.11 through 10.5.8 & the drivers may be available online from an archive.
IF the USB port is recessed, a USB extension cable may need to be used
to make a connection -- if the plug on the wi-fi dongle doesn't fit snugly.
The software drivers for the newer 802.11/n (even if it should be a/b/n)
USB wireless dongle won't work in the PPC versions of OS X if the
maker did not supply PPC drivers. x86 is an intel designation that
would imply later Macs after 2005 running Intel hardware.
• Did you see if the iBook G3 includes the optional wireless AirPort card?
These would likely provide no better than WPA; or base WEP security.
For best performance, an Ethernet cable is suggested, to ISP router.
If that model is a 'Clamshell' model see if the wi-fi card is inside...
https://www.ifixit.com/Guide/iBook+G3+Clamshell+Airport+Card+Replacement/105
...or white 'dual-USB' it's easy check or add card: {see amazon to buy Airport Card}
https://www.ifixit.com/Guide/iBook+G3+12-Inch+Airport+Replacement/120
The USB wireless adapter you have (aka dongle) doesn't appear compatible.
With recessed USB port, an extension cable may be needed for connection.
Doubtful a backward compatible driver would be available from maker.
A part number for an AirPort card (optional) is p/n 1001454; see amazon or
ebay resellers for best price. Also the original AirPort Express or Extreme
base stations may be a workable solution for separate wi-fi for vintage items.
A look back to when the 'clamshell' G3 was considered old:
http://newtonpoetry.com/2008/03/02/sunday-project-airport-on-a-g3-ibook-clamshel l/
Sorry to not be of more help. I used to have spare original AirPort wi-fi cards;
& still have few spare later AirPort 'extreme' cards & matched base stations.
Good luck & happy computing! 🙂