Yeah, google voice probably is a better choice.
I'm still leaning to Skype though because --
1. Unified. You can't actually make phone calls through an official google voice client but have to use 3rd party clients and other various hacks.
2. Uncertainty. Google might change up terms within a year or so, like they did with Google Reader.
3. Integration with Windows 8. I'm using a few Windows 8 devices, will probably be using this on a Nokia Windows 8 handset.
Still, google voice could be good b/c
1. supposedly has better audio quality
2. Should be cheaper. Though they lack an unlimited calling plan, they do give you a free phone number, which I still have from several years ago.
3. One number to ring them all? So I could give out a google voice number, and if someone rings it, my backup prepaid phone also rings? Haven't quite figured that one out.
I should have edited my post to be more clear but it's Unlimited calling to the US and Canada. Talk as long as ya like.
Yes one number to ring them all. You choose what phones you want to forward it too. If it's a non-smart phone you will have to dial your G-Voice number then there number if you want your G-Voice number to show up on there Caller ID. You can also set the non-smart phone to be unknown when calling out if you don't want that number to be displayed. Otherwise the Google Voice app on Smart Phones will display your G-Voice number.
Hell if you're at a friend's house you can pick up there phone & dial your G-Voice number then when the greeting plays press * and enter your pin. Then you can check voice mail and call people back and even set your friend's phone as a temp phone to ring! So if you have crappy wifi and are expecting a call while at your friend's House. This is just as an example.
Since it's free it's worth a try. Seriously why not? Even if they decided to become a pay model they would price it to be competitive to Skype. The whole free calling till next year is just a thing they put in to cover there ass in case they need to change it without getting a huge back lash.
I don't know what the Windows Phone store has in terms of apps for Google Voice. I will try and look later.
You can use Google Voice with Skype:
http://lifehacker.com/5878980/how-to-make-skype-play-nicely-with-google-voice
If you have any other questions feel free to ask. You can at least try this method and if it doesn't work for you.... Well there is always another thing to try, right? Got plenty of great suggestions here from others too.