Advent are predominantly made by a company called 'Centreprise', based in Basingstoke.
They are build specifically for DSG.
Sometimes alternate PC assembly companies are used to help keep up with demand.
The parts are normally quite generic, if not a little cheap and nasty, so getting it replaced shouldn't be too difficult.
Are you sure it's a mainboard problem?
If so, replace it with a board that will take your existing componants.
Don't forget, if you're on Windows XP, changing the board (Northbridge) requires a complete software re-install.
Redders
March 2008
Advent is a DSG Own Brand and so could have been made by anyone. Have you tried their technical support www.thetechguys.com ?
t
February 2008
Automatic Answer
While you wait for answers, we may have found some information which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix desktop pcs.