DNS is the "domain name server." Humans are generally more at ease with words while computers handle numbers better. Thus, we can understand google.com but the web wants to see it as 216.239.39.99. The domain name server is a computer set up by your internet service provider to translate your words into the computer's numbers.
You can tell if this is your problem by opening Pocket IE and typing
http://216.239.39.99/ into the address box. If it connects to google but
http://google.com/ does not, then your DNS may very well be the problem.
It's been my experience that your network configuration on the PPC (as well as the PC and any computer) needs the DNS in number format, so that may be one issue. Also, when I tried to ping gt01.aol.com, I got a 'could not find host' response which means that particular domain name isn't recognized by my DNS (if it had been, I would have told you to enter the IP number as the DNS rather than that name).
I'm not sure if AOL has some issue with PPCs - it's been a long time since I did anything with AOL. I know for IM people need to download a pocket version of AIM which was $20 in the US but free in the UK. There was a link from the downloads page here at AximSite to get it from the British site. Whether that will fix your problem, I have no idea.