Is XMLObject supposed to be a political statement or free software? If it's a political statement, GPL is the way to go. Otherwise, choose a less restrictive license and people may actually use your software. The Linux kernel, GCC, and readline are flukes.. the most popular open source software is more liberally licensed (Python, Apache, etc.). So what if Microsoft uses your source code? Are you more concerned about sharing, or forcing other people to share with you?