Go SIP and forget about skype.

My PC at home had become supernode, and skype used up all my bandwidth and monthly allowed volume. I know it is P2P-ish and uses users bandwith, but I don't want to give all my bandwith. So I removed skype and went with an open standard (SIP).

Using Gizmo5 now (works very well), but since they were bought by Google they aren't taking new subscriptions (for now). There are other free SIP service providers available though.