Well Windows XP pro i have heard is meant to be better for battery saving on laptops.
I doubt the setting for laptop or desktop would differ in performance.
To get to the hardware profiles > Start > Control Panel > System > Hardware > Hardware Profiles.
Now i have "Profile 1 (current)". If i click on Properties. The tick is NOT in the box next to "This is a portble computer". The options for docking etc are greyed out.
I'm guessing you have this box ticked.