If I remember scuttlebutt elsewhere, System Volume Information also stores SRPs/System Restore Points. If that is true, and those files are SRPs, almost all but the last 2-3 probably can be safely deleted. Somebody correct me if I misunderstood, thanks.
Addendum: I now realized my answer was incomplete -- I should have posted that the only safe way to delete SRPs is through...what tetraps posted. Follow tetraps advice, you won't go wrong.