I have tried for months to get this working on xp and failed.
I have a home network behind a FiOS router I don't know if protocol 41 is being passed but my linux box works perfectly as does the Mac, just the two xp systems do not ping any ipv6 addresses externally. I can ping6 all the other computers in the network from any box but the xp systems will not ping ipv6.google.com nor any ipv6 address. I believe the internal ping works because I have radvd running on the linux box so it assigns ipv6 addresses to everything. I have tried turning off radvd with no change to the external access but no more local pinging. I have tried running the xp system without the linux box running and get no access. I have tried the example commands for both win xp and vista with no access. Also using the local ipv4 address as an end point instead of the FiOS ipv4 endpoint but no difference. I do get a change in the response to a ping of either "Timed out" or "Destination address unreachable" but since I change too many things in between I'm not sure what changes produced this. I have seen both responses in the same ping. I have tried removing the ipv6 service then reinstalling it because I'm not sure if all my different settings are messing up the routing in windows. I tried to stop Teredo but I get messages that the command is not found but ipconfig doesn't show a Teredo route. I used a command that was suppose to show if the router was blocking the NAT or the NAT wasn't compatible with xp but it showed good but I forget what the command was. I understand that xp will try to use ipv4 addresses over ipv6 if it finds them but ping6 should override this.
I have run out of ideas on what to try next and am hoping someone has some ideas. It seems that xp can be used with this tunnel as others seems to have done it.