IIS—XP Pro includes IIS; XP Home doesn't. Encrypted File System (EFS)—EFS debuted in Win2K and lets you encrypt files on an NTFS partition, a very useful feature for mobile machines. XP Pro includes EFS; XP Home doesn't. Multiprocessor—XP Pro supports up to two processors; XP Home supports only one (as did Windows Me/Win98). Remote Assistance—Both editions support Remote Assistance, which lets someone from a Help desk connect to the client desktop to troubleshoot problems. Remote Desktop—XP Pro adds to Remote Assistance by letting any machine running a Terminal Services client run one Terminal Services session against an XP Pro machine. Domain Membership—XP Pro systems can be domain members; XP Home systems can't, but they can access domain resources. Group Policy—XP Pro supports group policies; XP Home doesn't. IntelliMirror—XP Pro supports IntelliMirror, which includes Microsoft Remote Installation Services (RIS), software deployment, and user setting management; XP Home doesn't support IntelliMirror. Upgrade from Win2K/NT—Only XP Pro supports this upgrade. 64-bit Support—Only XP Pro will have a 64-bit version that supports the Itanium systems. Network Support—XP Pro includes support for Network Monitor, SNMP, IP Security (IPSec), and the Client Services for NetWare (CSNW); XP Home doesn't.