Since all your USB ports work under Win 7 but not XP, then the problem under XP must be software related.
Did you examine the list of Services in XP? One or more may control USB ports. (The name of the service may or may not have USB in it.)
Look particularly at the services which are set to Disabled. If you spot a likely candidate, then change it to Automatic or Manual.
Or it may be a service which depends on another service, and that service is disabled.
There are several dozen services to look through, and see what they control, and to try enabling or disabling, etc.