How secure is LimeWire?

My current setup is a Windows 2000 Server acting as a domain controller and a Windows 2000 workstation. Both are connected to the net on a cable connection through a Linksys Cable router.

My server has an extra 8GB drive with operating systems and applications. My workstation has about 20GB of MP3s, Divx, Pron, etc.

I would like to share some of my data with other net users. Should I go through the trouble of setting up an FTP (I have a dynamic IP :( ) or just use a program like Limewire?

Would also like to know if this would have a major impact on my PCs' security.