Anyways, back to the my 3Com wireless router, checked the firmware version, being a discontinue product it was last updated a couple of years ago and the last time I talked to a 3com support person didn't help much... Turned back to the internet to find a few others having the same problem and no solution... Decided to keep poking around in the router menu, until I got into the Firewall > SPI section. Unticked a few options in Stateful Packet Inspection section, still no luck - then I took the courage and unchecked the main SPI entry and bulzeye! My box was talking to Bill's computers loud and clear!!! :-)
I don't have a full Xbox Live account, one of those gold ones (used to have one for the old Xbox, actually Microsoft was very nice and refunded me when it got renewed without my approval, but that's another story :-), I only needed to connect once to get the update. I might go back again every now and then for those free downloads or even get a gold subscription someday, although very unlikely given my spare time, I might have to decide to disable SPI for good. While I sorta do understand what SPI does, I'll need to understand it a bit more and give it a good run with and without to make a final decision.