macrophylla 'Merritt's Supreme' maybe? Just a wild guess though. Check out this photo for comparison:

http://1.bp.blogspot.com/_VAbdC3cvG7g/SoagZFac-BI/AAAAAAAAFhE/XeJLSzuv1bY/s400/hydgmerrittpinkwebcc.jpg

As far as whether or not it will survive, most macrophyllas would not be very happy in winter conditions as cold as yours, however, if you can find a sheltered spot and/or take care to give it as much protection as possible during the coldest months, it could do just fine. Alternately, you absolutely could keep it potted and move it indoors during hard freezes. It would be best to keep it outside the rest of the year though, as exposure to cold (but not hard frost) will allow the plant to properly enter dormancy each winter. Good luck, and maybe you can get some tips from some of the other folks up north on keeping beauties like yours alive through the winter! And if you ever grow weary of the battle, feel free to bring her back down to where she came from- we've always got room for another hydrangea lover here in Georgia ;0)

That does look like it. I have the perfect pot for it. I bought a mosaic tyle planter that I used as my (adult) kids' Easter basket.
I was hoping to be able to plant it which is a lot less work than moving it back and forth, but I will give this a shot.
Thanks for the offer to adopt it! LOL.

Plants found for sale now in bloom will be greenhouse or florist's hydrangeas. And they are often (even typically) sold without identifying names. It is very difficult to assign a specific cultivar name to them as the greenhouse forcing process often involves complicated procedures to modify flower color and bloom size - what you see now is not necessarily what you will get planted in the ground.

Most macrophyllas are root hardy to zone 5 although they will be damaged by winter cold unless they are protected. Often, greenhouse hydrangeas do not show the same degree of hardiness as those grown naturally for the landscape. Growing it in a container may be a good alternative, as it can be more easily moved indoors for winter protection.

Hydrangeas do not make good houseplants - ones sold like this are generally intended as temporary flowering plants. If you do grow it on in a container, it will need to be hardened off or acclimatized to the outdoors before you can move it to a porch or other location. And winter protection can be as simple as just moving the container to an unheated basement or insulated garage -- somewhere cool (some freezing OK) so the plant can go through a normal period of dormancy. Bringing it into your living room or elsewhere under normal comfortable living conditions for the winter will alter the natural process and can create problems.

Greenhouse Hydrangea was actually the first thing I thought...not sure though. First, because I didn't buy it at Home Depot or Walmart. It was at a huge nursery that sold trees, shrubs, etc and I didn't see anything else there that would have given my that idea. Also, it just seems bigger and more "solid" (for lack of a better word) than a typical greenhouse plant.
I guess it will be just "wait and see".

On the greenhouse plants subject... I have a friend who planted a florist's hydrangea that she was given as a gift. I told her it would never survive (our winters frequently go to single digits for weeks at a time). That was about 4 years ago. It has come back and flowered every year. Got lucky I guess.

Since hydrangeas do not bloom at this time of year, it is definitely a greenhouse plant.....forced into bloom out of season and at a very early age. In my area, these are sold by nurseries as well as groceries, florists and box stores but as gift plants, not landscape plants (although they do transition well here to the landscape).