It is possible to put Windows Movie Maker 2 onto a Windows Server 2003. It doesn't mention it on Microsoft.com, but you could buy it from Microsoft (no download available, believe me, I went 2 months searching). You could either write a software patch to allow multiple accesses to the software, but generally, you should be able to download one from
Software Patch. I haven't tried this myself, I just found it easier to buy a copy with 5 licences (allowed to install on 5 pc's).