Whilst installing the gargantuan Service Pack 2 for Windows XP I was presented with the following balloon message:
For most people this message would be fine, but I am one of the people who have taken advantage of the personalisation allowed by Microsoft and have moved my Taskbar to the top of my desktop rather than the leave it in the default position at the bottom of the screen.
I prefer to have my Taskbar at the top because it feels more natural for menus to 'drop down' rather than 'jump up'. It is also more efficient as we all know that gravity means that menus will drop down faster than they can ever jump up.
The person who designed the text that appears in the ballon message obviously doesn't know that it is possible to move the Taskbar. This is not surprising as it was made much more difficult to move the Taskbar when XP was introduced.
By default, the Windows XP taskbar is locked in position. Microsoft has received a lot of feedback from users who inadvertently move their taskbar, often causing it to become invisible or to take up to half the screen.From Usability Improvements in Windows XP for Knowledge Workers.
I think that Microsoft should have never allowed the Taskbar to be moved by the user. They must have designed the Taskbar to work most effectively when positioned at the bottom of the screen, so why didn't they have the confidence to stand by their design and leave it at the bottom of the screen?
When Microsoft designed the Pocket PC they didn't make the position of the Taskbar user choosable and no-one complained.
If you decide to allow users to personalise aspects of the interface then make sure that everything you add to that interface works in all of the available permutations.
I would recommend that you never use persoanlisation. Instead, design the best solution you can and present that your users, they won't complain about the lack of personalisation if your design is a good one.
PS: Take a look at the movie clip from Adam Kontras entitled "Lock The Taskbar" (to the tune of 'rock the casbah').