I have to word this very carefully as I don't have any technical details.

So I'll just write my experience.

I have Skype installed but don't have any headset so I've not used it.
I then see the news item about EpyxMobile and the use of bluetooth enabling mobile phone use.
That's my answer I thought.
I had to upgrade Skye to v1.3.0.57 (No problem)
I then installed EpyxMobile and peered my T610 mobile.
It all connected with no problems.
I then read the EpyxMobile user guide (It wouldn't have been right/natural if I'd read it first, to find out what I was doing. :-)

I then found that EpyxMobile was not what I was looking for and thought no more of it.

Next day (today) I logged in and EpyxMobile automatically started.
I closed it and removed the auto-start option.
I dialed up my modem connection. Nothing!
No bing bong dialin tones. Checked sound and it was muted. un-muted it.
Still no sound. Checked iTunes. Nothing.
Maybe there's other WindowsXP enable your audiocard options I'm not aware of.
I'm sure there are.
I do remember that Skye now has Bluetooth support in it's own right.
I also remember that I'd seen all sound device options set to bluetooth.
The problem I had was that I couldn't access Skype as there was no network connection.
Chicken and egg. Maybe I didn't wait long enough for Skype to time out and give me Skype off-line access.
I then went back to my last restore point and reloaded my WindowsXP PC.
Logged back in. iTunes works. Dialin works. I'm happy.
Re-installed Skype and set the sound device options to Windows default device. ;-)

So... Creating WindowsXP restore points and restoring works!!!
It's a God send for wombats like me that don't know their way around a PC.