Back from holiday- sorry for the gap in posting!

I'm guessing you've already checked to see what graphics adapter you have, because obviously if it's not the same as mine the driver may not work. OTOH, if this is a recurring problem with this specific adapter that we both have, hopefully this thread will help them too.

Save a system restore point before the next bit, if you're at all worried about the outcome.

You can force an install- in Device Manager, select the Porpeties for your display adapter, select Update Driver, opt not to search the Internet, Install from list or specific location, point it at wherever you unpacked the driver to, and then select the options that go ahead with the install despite it's complaints that it's not the best driver.

Restart and check back in device manager that it's got the correct adapter listed, and hasn't created a second one or something like that.

If none of that works, maybe try fitting a new card?