Well I've had a white iBook G3 in the past & I currently use a PowerBook G4 Titanium as my main portable. If you have a decent budget, of say £200 ($300) I'd say get a 15" 1.67ghz PowerBook G4. They have built in Airport extreme (802.11g) and you can stick 2gb RAM in there. But if you're on a tight budget, eg. £100 ($150) I'd go for a PowerBook G4 Titanium, while looking to get the best bang-for-buck G3/G4 Mac laptop I narrowed it down to either an iBook G3 or a Titanium PowerBook G4. I went for the PowerBook for a few reasons, it has a 15" display (could be a good or a bad thing to you), it can take 1gb of RAM (the iBook G3's can only take 640mb RAM), it can run Leopard which is a huge bonus, trust me, Leopard can run so much more applications and software than Tiger, but you probably know that anyway. But the real deal breaker was the fact they were the same price near enough. I got my 800mhz Titanium PowerBook G4 with Airport, 40gb HDD, 1gb RAM, Leopard etc. for £60 ($90). And that's in the UK where EVERYTHING is more expensive.
Everything I based my answer on comes/came from eBay, I buy everything from eBay 😛
I Say Get A PowerBook G4 Titanium, You Won't Be Disappointed!
EDIT: Just in case you don't know, the Titanium PowerBooks and the G3 iBooks (clam & 2002 ed.) take the original Airport cards (802.11b)