Is there a reason for that though? Newer operating systems, or at least the ones I use, can read UDF discs fine. Since the DVDs are personal backups, it's not a matter of compatibility that's the issue. I'm wondering if there's any technical or specific issues with UDF that I should know about. Especially since I believe that even if you use a hybrid disc, that Windows XP will favour the UDF system over the other. So using a hybrid disc in Windows XP is essentially the same as using just UDF.