What is it?
Windows Media Player Service- MsPMSPSv.exe

What does mspmspsv.exe do?
This is a helper service for Media Player 7+ which adds support for Windows Media Device Manager which is stuff like your portable media devices. If you don't take your music with you then this service can be disabled. This

Virus Precautions:
You'll want to keep an eye on this google search for any known viruses. The normal location of mspmspsv.exe is gystem%MsPMSPSv.exe commonly: C:WINDOWSSystem32MsPMSPSv.exe. At this time my search shows nothing that you need to worry about.