A colleague of me [Patrice Verrecchia] has received a new PC with Windows XP. We have downloaded and installed:
WindowsXP/NT/w2000 with VC++ 9.0, version 5.22/00 (good old tar file) (49.4 MB).
We have correctly defined %ROOTSYS% and put %ROOTSYS%\bin into %PATH%.
But launching root failed, with a message [from Xindows XP not from ROOT] saying something like “not correctly installed”.
Installing then the free version of Visual C++ solved the problem. Could you advice ROOT users on Windows XP that they have to install the free version of Visual C++, or give a simpler way to have ROOT working? Thanks a lot
Hi Francois-Xavier,
In fact, only the Visual C++ 2008 Redistributable Package is needed:
http://www.microsoft.com/downloads/details.aspx?FamilyID=9b2da534-3e03-4391-8a4d-074b9f2bc1bf&displaylang=en
We are currently re-organizing the ROOT web page, and this will be added to the Windows specific pages.
Thanks anyway for the (always useful) feedback! 
Cheers,
Bertrand.