PRoblem upgrading software for Microphone

Hi,
I tried to use my headset for Skype and I could hear the test call person
but I could not be heard by the system, I tried to configure the microphone
but Vista tells me it is working properly so I visited the manufacturers
website and downloaded the Vista drivers for my sound card,(realtek) it came
down as a zip file, I opened the zip file and clicked on setup.exe and the
installation began, it has go as far as 97% and I have started receiving a
message saying the driver cannot be verified by Vista do I want to continue
installing?, I click "continue anyway" and the pop up box disappears only to
re-appear 30 seconds later and I have to click "continue anyway" again, this
is happening all of the time, how can I get this driver installed?
Thanks,
Noel.