I've been using this program since before its official release, and I've been amazed by how well and stably it runs Windows XP Professional. I use it nearly every weekday at work to run AutoCAD for blueprint drafting, and it has very rarely failed me, and even then, I'm fairly certain that the instability of the Windows operating system itself had a great deal to do with that. I haven't tried any alternatives, so I don't know how it measures up to other applications of this nature, but I've been very satisfied with Parallels so far. The only thing I seem to be having repeated trouble with is having Windows recognize blank CDs. It doesn't seem to want to allow me to drag and drop files onto the CD drive icon. I'm not sure if Parallels or Windows is to blame for this, though. In any case, this is a small note when considering the incredible stability of this application in general.