"Yes, Virginia, There is a NAP Client for XP"
Having written my book on Server 2008, I've been doing quite a few "Sneak Peek" presentations for Microsoft on the topic of their new O/S. One of the questions I get asked the most has to do with Network Access Protection and its support for XP clients.
"So Greg, does this new Network Access Protection work with XP or do I have to wait until all my clients have been upgraded to Vista?"
(That question is usually followed by a classwide harrumph, since many administrators still believe it'll be a cold day in heck before they move to Vista.)
The short answer is yes. But only once you've upgraded your XP clients to SP3. The bits and bytes for the NAP client will be released in SP3, but some additional work is required to get it completely set up. If you're interested, I discovered this page recently over at The Lazy Admin that talks about those steps.

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