hi,
is admin$ shared , can you coonnect to these xp machines from SEPM .
Is the password blank on Win xp, if yes enter some password and try pushing the client package.
also under Network access: Sharing and security model for local accounts- select to classic mode ( this is for Win XP). You can do it by opening control panel , administrative tools , local security settings , local policies, security options under this "Network access: Sharing and security model for local accounts" chang ethe value to classic.
Port 445 and 137, 139 are open on win xp . refer installation guide. or disable firewall.
Pete!