As my G4 does not have an airport I will have to find an alternative way to connect it to the internet.

A few methods come to mind.

1. Devolo plugs to router then to ethernet on G4 but never tried power plug networking and costly at £40 for two plugs not including cat 5 leads.

2. Internet Bridging via dedicated bridge. Once again quite costly but guaranteed speed once again connecting to ethernet.

3. Cross over cable from laptop or G5 sitting next to machine. Cheap but probably a nightmare to set up.

Any other suggestions on how I could do this?

Atheros based PCI card should work too (and is probraly <10€).

BTW, the "power plug networking" does work. I have 4 of them and one is hooked up to my G5..works great.

I've succesfully tested two options:

1. As suggested by Kronos - PCI WiFi card with Atheros 500x chipset. I've succesfully tested TP-Link TL-WN 350G card in Power Mac G4 and Pegasos II. Costs less than 10 EUR.

2. WiFi minirouter in client mode, connecting to your home WiFi network. I've succesfully tested TP-Link TL-WR 702N and use it currently with Mac mini (my mini has no AirPort module). Costs around 20 EUR.