Yes, vcredist_x86.exe is the right one to install for XP (or 32 bit versions of 7/8).
You shouldn't be getting the installation every time you start the game. Try uninstalling the VC++ runtime files from the Control Panel 'Add or Remove Programs' applet, reboot, shutdown all non-essential applications and try installing it again as administrator.
An old topic elsewhere recommended the program 'Windows Clear up Utility' to make sure vcredist_x86.exe was completely removed before reinstalling, but MS has
replaced it with the
Program Install and Uninstall troubleshooter, which you could try if a normal uninstall/reinstall doesn't help.
If you haven't done so already, try emailing support@larian.com, with a description of the problem and maybe a link to this topic.
