Because Apache and MySQL were designed originally for *nix type OSs that do not use spaces in file names rather they use an underscore in place of a space.
In Vista there may be other reasons why not to use folders with a space in the name that is quite adequately explained here under
Vista Note:
http://www.apachefriends.org/en/xampp-windows.htmlAnd here under
Vista problems:
http://www.apachefriends.org/en/faq-xam ... html#vistaBecome a
Secret Super Administrator in Vista and perhaps you will be able to overcome some of Vista's needless and mindless limitations that have been put in place by the MS team of Controllers (nannies) for absolute new first time computer users.
As a rule of thumb in XAMPP never use a file name or a folder name that has a space or any special characters in the name and preferably use all lowercase letters for the naming of files and folders.