Standby

I have a DVRaptor card for DV capturing. It is an old card bought around
2000 but it still works well. During this period, my system has changed from
Asus P3V4X, to Gigabyte 8IGX, to now Gigabyte P35C-DS3R. But it has a
problem with these mobo (I guess it is related to mobo). If the card is
inserted but not its driver, the Standby option is available in the Shutdown
(I am using xp sp2) window. But after installing the driver, the Standby
option is grey. I've tried all slots (to use different IRQ) of all these
mobo and ended up the same. When this happened with my first 2 mobo, I
thought it might just be the mobo not supporting Standby, and Standby was
not particularly useful to me at that time. So I just didn't care. Now I
have a 8800GTS in the system which is quite hot. I am thinking of using the
Standby if I have to leave the system for a while.

Anybody has any idea why the Standby doesn't work with the DVRaptor driver?