Xbox 360 owners looking for a hard drive upgrade might have some trouble finding a 120GB hard drive upgrade. According to the word from our sources, the 120GB hard drive is in short supply and supplies are limited only to stock on hand; as our sources report that they are not receiving replenishment inventory from their warehouse right now.

While our sources say that no replacement larger drive has shown up in their systems yet, they believe that it is now likely that Microsoft is moving to clear out inventory prior to the introduction of a new larger model.

The current Xbox 360 Elite ships with a 120GB hard drive and the special limited edition of Call of Duty: Modern Warfare 2 and Forza 3 bundles that have become known as the “Super Elite” editions included with a 250GB hard drive. While the Forza 3 bundle was only sold outside of North America, the Call of Duty: Modern Warfare 2 was sold in a variety of territories.

From what our sources tell us, supplies of the Super Elite editions are limited to whatever retailers might still have on hand, but retailers that we have checked with claim that they have been told by corporate to expect no additional “Super Elite” inventory; and while they might get some additional regular Elite holiday bundle units in the short term, they are being told to expect a new Elite package to arrive soon. Our sources are claiming that they have no idea what may or may not be included in this new Elite package.

What our sources seem to expect, although we can’t confirm it yet, is that we will see a new 250GB hard drive upgrade to become the new standard to replace the 120GB model upgrade model. In addition, we hear that Microsoft will be making a transition from the Elite with the 120GB hard drive to an Elite that will contain the 250GB hard drive. The reason that Microsoft can do this is that with the reduction in hard drive prices and increases in hard drive areal density, they can do the upgrade for free while adding value for the customer. We think it is likely that the new Elite package will not carry a pack-in title to increase the margin and will be re-introduced later this year in a special game-of-the-year (GOTY) edition that will include a pack-in title.

In the meantime, if you have to get your hands on a 120GB hard drive, expect that you may have to spend some time looking if you want a new one; or you may have to just settle for a refurb or a used one. The only other option is to wait for the introduction of the larger hard drive, or if you are just looking to add a hard drive to a recently purchased Arcade unit, you may have to settle for the 60GB hard drive, which still seems to be in ample quantities with the retailers that we checked with.

As for when you can expect to see Microsoft launch this new larger hard drive, it is anyone’s guess at this point. We did expect an announcement at CES, but it is clear that inventory levels were not at the point where Microsoft was ready to make this announcement. We do expect to see it before E3 in June, if that helps, and our sources seem to agree that this is likely the case.