Which account do you sign in as?

I already have a Skype username and contacts which one do I sign in with to access Windows Live and have them show up with my Skype contacts? I swore I asked this once but I really don't recall. >_< I haven't switched yet but plan to sometime very soon just wondered which one I'd have to log in with.

Any update on if the contact loss during the merge is over with? My mom merged and didn't lose any but she didn't have a Skype account already and she only had me and dad anyway so if she lost them it wasn't that bad either way.