In a surprise move, Microsoft has announced that effective immediately they are making the Xbox 360 250GB Hard Drive available in the North American market. (We expect confirmation for a European release soon, as well.) Previously, the 250GB hard drive, while available in the Japanese market, had only been available in North America in the Xbox 360 Special Edition and Limited Edition console releases.

The news of immediate availability comes on the heels on our sources telling us that we should expect an announcement at E3, but Microsoft appears to have decided to bump up its release. According to our sources, the 250GB hard drive upgrade package will include both the transfer cable as well as the transfer disc to allow users to migrate from their current hard drive to the 250GB model.

As for the previous 120GB model, Microsoft will be dropping the price of the 120GB model to $99.99 from $129.99 while supplies last. This news does confirm our assumption that Microsoft will discontinue the 120GB model when supplies are exhausted. As for the 60GB model, which also has been selling for $99.99, we assume that Microsoft at least for the time being is going to continue to offer that model.

The new 250GB model will take over the $129.99 price point that was previously held by the 120GB model, making it an excellent value; but those that need a hard drive right now may want to quickly seek out the 120GB model, which is an even better value for $99.99. Of course, a check with retail contacts indicates that supplies of the 120GB model are tight or they have none left in stock. We have also been told by the retailers that we checked with that they don’t even see the 250GB hard drive in the system yet, so it will likely be a few days before it shows up on retailer shelves.