[Aragorn]

Mirroring does not protect against software failure - even on corporate disk arrays you can, in theory, write zeroes over the payroll database - but it does protect against hardware failure of one disk. You should still do regular CD/tape/network backups of you important data.
Stripping only improves performance - no hardware data protection at all.

If you want to be cautious about your data, I would personally suggest sticking with the mirror, but stick a third cheap IDE drive in as an online backup. You can schedule XP's own backup util to write to a compressed disk file, and also have a second bootable copy of XP on that drive incase you need to restore.

HTH