A number of customers I work with have been keen to identify a Windows Mobile device as a potential laptop replacement. Now it all depends on your job as to whether such a device could deliver that for you however Jenneth has written an excellent article on GearDiary as to how she is using her HTC advantage as a laptop replacement.
Jenneth is using a combination of 3rd party applications along with the inbuilt Windows Mobile apps to acheive her goal.
I must give this a try as right now my HTC advantage has become more of a demo device due to the fact it is so well specified (GPS, 8GB Drive and VGA out) and the fact I can load a huge array of applications to it!
You can check out Jenneth's article HERE