Realtek NIC card driver problem - unable to configure VLAN..

Could someone please help me? I am using a Realtek NIC card, that
allows VLAN tagging, on a Windows PC. I have used the standard route
of going to the Device Manager and trying to configure the NIC card so
that it can tag outgoing packets with the VLAN ID, but on examining
the packets with the Ethereal tool, I do not find the characteristic
VLAN ID in the Ethernet II header, as it ought to. Is there something
work with the driver or am I doing something stupid? Any hints or
suggestions would be greatly appreciated. Thanks in advance for your
help.