What hardware do I need get an this particular iMac to connect wirelessly to my 802.11n (Airport) network?

Dese kids, they grown up so fast. So’s I had the idea to get my 3 yr old daughter her own computer; she loves climbing in my lap and trashing the OS of my MacBook in that cute way only toddlers can manage plus she’s tech-savvy enough to start/stop “Bolt” on the AppleTV 37 times a day. They only have some antique windoze(?) 95 thing at her pre-school so I found her an old iMac on Craigslist.

Here’s my prob: her xmas present has no wifi for connecting to her movies OR for playing the plethora of free product-tagged online “educational” games. I’ve bought a couple of 802.11n USB adapters, but although they show up in System Profiler, neither of them are seen in the Network Preferences. ( I think I’m supposed to be seeing “en2” or something.

Anyway: what hardware do I need get an this particular iMac to connect wirelessly to my 802.11n (Airport) network?

Again, it’s a 1.25gHz iMac G4 with 1.25 RAM and no installed Airport.

Thanks, y’all