from the angle of Skype, I use a linksys CIT400 (now superceded) IPhone - yes the original IPhone before IApple decided they owned everything with a letter 'I' at the front...
it is a dual mode telephone, VOIP and landline and connects to your LAN through a switch or router, so no PC needs to be turned on. Calls to almost anywhere in the world cost under 2 cents a minute, cheap, reliable and works just like a normal phone AAND a VOIP phone whenever you choose without leaving the computer on.
since I got the linksys phone, there has been at least 10 other come onto the market.