Is this even possible, do I have the right tool in mind? I have 3 disks that are running as a software RAID5 using windows. I would like to migrate box to Linux without experiencing data loss. Am I dreaming?
You want to keep the data in-place? Then yes, you're dreaming.
If you have 3 separate disks of equal or greater capacity, you could create LVM PV's and LVs on the new disks and copy the data over from the old disks, but that's about it.