You will not find any drivers for Windows XP on NB500 because this old Windows version is not supported. Everything what you can download on Toshiba website are drivers for Windows 7 but Windows XP is not supported.
We have year 2011 and all new devices are designed to run with Win7. All new notebooks have newest hardware inside designed for new standards. Why do you want to use old operating system on newest generation notebook?
This model is not even supported for old WXP and that is the reason why you cannot find drivers.
I’m really wondering you have installed WXP before checking WXP support.