Hi I am using Majic Jack also. My sister sent it to me from US. she paid 19 $ for 1 year. I had a 512Kbps Unlimited connection before, but the voice breaks you need a faster connection. with magic jack you get 1 US number of your choice but then they charge you extra to change the number, it connects through your usb (needs USB 2.0). I had problem running it on XP but works fine on Vista. Is NOT compatible with Linux. (atleast not yet) they have a CC online so you can talk to them for details and charges.
You also get Voice mail with it, which can also be forwarded to your email. Also in order to recieve calls, you need to have your computer on. Which is a problem in case there are powercuts here in India. Over all, I have used Skype and Majic Jack. Usability wise I think Skype is more flexible as you can install on your phone, and just use it from your mobile device, I was using it on
iPhone, with 10$/month world wide Subscription or I think 5$ for US/Canada.
Majic jack is also good, but the fact that you have to leave the computer on all the time in order to recieve calls makes it a little bit Unfriendly towards the user, also If you have wireless on the
laptop you can just connect it to that.
Over all Voice clearity is equal for both, but since Upload rate for most data plans is low you need to get a plan with good upload rate, AND no i dont think it will work with 64Kbps.
edit: I just checked the Pack (in which it came) it says its for 39.92$ from Best Buy, and any additional years subscription is for 19$ and well they have new offers all the time so go check out their website @ www.magicjack.com