Microsoft (MSFT) is talking about Windows XP, Windows 7, and the enterprise again.

For the moment, put aside any concerns over Microsoft's flagging online presence or the long-term threat of Office-competitors like Google (GOOG) Apps. The biggest problem for Microsoft over the next 12-18 months is whether enterprise customers, a whopping 71% of whom never upgraded off Windows XP, will embrace the upcoming Windows 7, or whether they'll stick it out with XP for years to come.

The specific problem: While a Vista-to-7 upgrade seems easy, upgrading from XP-to-7 (or even XP-to-Vista, which is how Microsoft got stuck in this hole in the first place) is a major headache. For an enterprise client with thousands (or tens of thousands) of PCs, upgrading off XP could easily be the most difficult and/or expensive IT deployment a company will undertake all year.

We heard CEO Steve Ballmer tell CIO mag that corporations should move to Windows 7 because "people will ask their boss why the heck they don't have the stuff they have at home." Now that's not the stuff corporate buying decisions are made of, and Steve is smart enough to know that. Which underscores how Microsoft is grasping at straws to get their corporate customers to undertake major IT upgrades amidst the recession.

But we credit Microsoft this: Once the company has a plan, it doesn't back down. Over on the Microsoft Windows Blog, the company is debuting a new set of tools to help corporate clients plan their upgrade. And in a stunning display of chutzpah, Microsoft is urging their customers still on XP to upgrade to Vista (which they've avoided all along) first:

We know some of our customers are considering waiting for Windows 7 instead of deploying Windows Vista today. We want these customers to understand the following considerations, so they are not surprised later on:

You may find your company in situations where applications are no longer supported on Windows XP and not yet supported on Windows 7...

We expect deployment and application migration from Windows XP to Windows 7 to be similar in effort to going from Windows XP to Windows Vista. As I mentioned above, there is a great deal of compatibility between both Windows Vista and Windows 7, as we are not introducing any major architectural changes. Our customers who focus efforts in getting their applications to work on Windows Vista will ease future migration to Windows 7 and help accelerate their Windows 7 deployment.

Nice try, but no one is going to upgrade Vista now.

What we still don't hear, and what we're starting to fear there's no good answer for: Other than the fear of having official support for Windows XP applications cut off, just what exactly are the quantifiable, ROI-generating benefits of Windows 7 for the enterprise? It's certainly not "touch."