Now Simon you know it can’t be his super PC or his ISP. It has to be WGT.
If he can connect to other sites (but not WGT) just fine, it's a problem with the connection to the WGT web server. That points to either WGT or his ISP. Most likely it's on WGT's end if other web sites are coming up fine for him. Hard to know for sure unless you're running some sort of network capture / trace software, e.g. Wireshark. But that's well beyond the expertise of the average user.