If it turns out it's needed by some program, you can either reinstall that program or download a fresh copy from Microsoft. They do have free versions.
I have a basic, older, and slow XP machine and decided to get rid of a few unused programs. I ran across Microsoft SQL Server and sub programs that are taking up roughly 250MB of HD space. I have no idea if this is something used automatically by other programs, but I have never tried using it myself. Is it safe to ininstall these?