Adding to Rafeeq's comment,
While you
can install SEPM on an XP machine there are several reason - unless you have no other choice - why you shouldn't.
- SEPM system requirements vs. XP desktop resources
Min RAM requirement for SEPM is 1GB, recommended is 2. This is dedicated RAM for SEPM, not total system RAM. There's a lot going on in the background w/SEPM, sharing resources on an already busy XP machine will most likely be an exercise in frustration.
- Desktop hardware vs. Server hardware
While SEPM may not be as mission critical as Exchange or SQL for your environment, it is managing a portion of your security infrastructure, and really needs to be on the most reliable platform possible.
- XP vs Server 2003/2008
XP is has been our friend for going on 9 years now. While no roadmap has been given, you know Microsoft is going to start down the road of retiring XP at some point. So from a pay me now, pay me later perspective, you're investing time now that will have to be duplicated if/when you have to move SEPM to a newer OS.