If your problem is not being able to resolve names, then you need to check your DNS settings. I've also found that every now and then Windows requires that you manually enter in DNS information to the connection settings, because it can't seem to get it from the router's DHCP server.
I'm running windows xp sp2, I can not ping any computer names but I can ping all internal and exsternal IP address. This happened after I disconected cat5 and added another computer Windows xp pro and a Belkin wireless G router. computer are wired. xp pro machine running ok.