When NASA first started sending up astronauts, they quickly discovered that ballpoint pens would not work in zero gravity. To combat the problem, NASA scientists spent a decade and $12 billion to develop a pen that writes in zero gravity, upside down, underwater, on almost any surface including glass and at temperatures ranging from below freezing to 300 C. The Russians used a pencil.

From: http://www.laughlab.co.uk/

This is not a Windows XP tip, but a frequently asked question. After installing Adobe Acrobat Reader v6.x, you may notice the My eBooks folder appearing within the My Documents folder. This is not a standard Shell folder of Windows. Even if you delete it, this folder is recreated upon loading Adobe Acrobat Reader.

This is powered by a Adobe plugin 'ebook.api'. Upon starting Adobe Acrobat Reader, it loads all the plugins under the following folder: 

C:\Program Files\Adobe\Acrobat 5.0\Reader\plug_ins

Perform the following only if you don't plan to use the eBook plugin of Adobe Acrobat reader. You can undo the operation though. If you don't want to see the My eBooks folder, follow this solution:

Move the file ebook.api to the following folder:

C:\Program Files\Adobe\Acrobat 5.0\Reader\optional

Delete the My eBooks folder now.

(Thanks, and credits to MS-MVP Wesley Vogel for this tip)

At a later stage, if you again want to use the eBook plugin, revert it back to the plug_ins folder.