I crossed my fingers and tried the screensaver hack - and my lovely hubby is staring out at me from one of the 5 photos of him I put on there

. I did have a few odd moments - though not 'brick' ones, when it appeared to not recognise some of the files and flash a grey screen at me, but this was solved by a complete Restart and then voila! Alternating screensavers as it should be.
I've turned off wireless for the moment so I don't have to get the standard ones back, and I'll be watching for when the 2.5 hack is done.