To summarize the answers here and to inject my own advice:
1: Blindly shrinking a data file is not the best route. Your data is your data and it is characterized by this size. Unless you are planning on deleting large chunks of data, shrinking is not going to do much of anything. As @billinkc pointed out, simply shrinking the file will not give you any sort of appreciable gain.
2: Running this is going to make your log file grow. Apparently you have your data and log on the same drive. I'd recommend against this for many reasons including space and IO contention.
3: You can certainly create a new data file and put that on a different volume. You could "archive" old data to free space in the current .mdf, or you could leave the current data file as-is and it would become an archive, of sorts.
4: I'm guessing that there are other things on this volume as well. I would move those things as quickly as I could in order to free up space.
If this is enterprise data, I'd push for more disk. This would allow you to separate your data and log files. Additionally, outside of just deleting data, you're going to need more disk to implement Brandon's suggestion anyway.