This one is a little weird, on my home PC (that's running Vista 64 home premium), it sometimes fails to connect to the network properly on bootup.
As far as I can tell it's a DNS issue, I can get to my home page (Yahoo! UK & Ireland), but trying to navigate beyond the front page fails, as does loading any other pages. The only way I've been able to solve it means I have to reset the machine.
My home network's fairly simple, a Belkin Wireless ADSL modem/router, which I use MAC address filtering on and DHCP to assign IP addresses, DHCP lease is set to "Never Expire". The only permanently connected item is the printer, which I've manually assigned an IP address above the range I've allocated for systems (assigned .2 through to .200 to the DHCP)
I also note that the IPv6 is always displayed as "Limited", I presume that it's a case that the router isn't capable because it's a fairly new standard?