Well after a bit of a wrestling match, I did finally manage to get our friend connected to Talk Talk! It was quite a challenge though.
First of all, their CD installation wouldn't run on the older version of Internet Explorer that our friend had. They had supplied a more up-to-date version on the CD, but you had to search for it. Not at all intuitive.
Even when the Internet Explorer had been upgraded, there were some missing components - something to do with scriping and install on demand. Because the TalkTalk CD had already hi-jacked the internet settings, it was quite messy to get back to the old dial up acccount to get these bits sorted out. In the end, I did what I should have done in the first case, and did the install without the assistance of the CD. I located the modem drivers on the CD and installed these. This put a new icon on the desktop, and I was able to double click this, enter the username and password, and connected to Broadband no problems.
I am still worried about the problems connecting that you guys are talking about, but for now, at least, our friend is happy!