I'm pretty sure you can just partition your HD install snow leopard on the blank partition and upgrade that partition to Lion. You would then have SL on one partition and Lion on another. I think that would work. Having lion does not mean you need to upgrade to iCloud either. You could probably stick with Mobile me and ignore iCloud.
Thanks, I'll look into the idea of partitioning a bit more.
As far as MobileMe goes I was under the impression that if you didn't move to iCloud by June 30 you were out of luck as MM will no longer work at all.