Software :: Unable To Access Update / ITunes Store

I have used an iBook G4 for a year and a half I only use wireless Internet connections. I recently started getting error messages when I tried to perform a Software Update. The error reads: "Software Update can't connect to the update server. Make sure you're connected to the Internet, then try again. Software Update can't check for updates because of a network problem."

Perhaps at the same time (I hadn't paid too much attention at first) I found that I was unable to connect to the iTunes Store. This error message read: "iTunes could not connect to the iTunes Store. The network connection was refused. Make sure your network settings are correct and your network connection is active, then try again." A google search shows that the second error message is common among PC users who think apple is conspiring to keep them out of the iTunes store with iTunes v7.1.1. I don't know about network settings but I don't make a point of ever fiddling with them. I assume both of these problems are symptoms of the same network mess-up. Can anyone steer me clear?