Intel Pro/Wireless in X20 -> no Powermanagement?

[rev]

Hi,
Last week I put an Intel Pro/Wireless 2200BG MiniPci Card in my X20.
I had no problems installing the drivers and connect to my Access Point.
But:
With the installed card, the Maximiser showed me about 18W Power consumption (~2.4Hours Batt Life),
even if i deactivate the Radio!

I found out, in the properties of the card, in the Device-Manager (WinXPSP2)
there was no Button with "Computer may deactivate the Device to save power".
How is this? With the original shipped LAN-Card I have this Button, and the Thinkpad only consumes 8-10Watt and it shows me much more Battery lifetime.[/i]