Make sure Task Manager is showing Kernel time as well as User time. (View menu, Show Kernel Times). If a kernel component is consuming the power, then it won't necessarily show up in the 'green' of User time. If it's mostly kernel, that's indicative of graphics, disk activity or memory activity (big simplification), and could indicate a problem with a device driver. Sorting the task manager columns by 'CPU time' might show more info, since the cumulative totals will be grouped together.
I'm not familiar with Vista, but in XP I'd next try Device Manager (in XP, it's right-click 'My Computer' select Manage then Device Manager). Look for any yellow question marks. Try right-clicking in DM & 'Scan for Hardware Changes' & see if your missing wireless etc. is re-detected. If it were me & if there was 'yellow' hardware, I'd probably use DM to remove it & then ask DM to rescan, hoping that it would correctly pick it up. However I'd be wary of advising someone else to follow my advice unseen, in case it made things worse! Perhaps best to create a Restore Point before you try any of these.
You could also look in event manager (eventmgr.exe from start/run) and see if there's anything odd there.