Microsoft – which has yet to get its tit out of the legal wringer it got caught it because of the famous “Vista Capable” promotion – has started trying to discriminate between Windows 7 SKUs now, a year ahead of the operating system’s ostensible due date.

The company said Tuesday that of the myriad versions of Windows 7 it intends to propagate, most consumers will be best served by Windows 7 Home Premium and most businesses by Windows 7 Professional, the latter described as a logical alternative to Vista Business.

It says Windows 7 is different from XP or Vista in that its editions are supersets of one another and keep the features and functionality of the versions below them. And apparently all the versions can run on all hardware from netbooks on up to fancy gamer rigs on the theory that people have more than one device.

Enterprise customers will be encouraged to adopt 7’s Enterprise Edition, which will only be available from Microsoft, not at retail or preinstalled on new PCs by OEMs. It will offer advanced data protection, lower cost compliance and management tools.

Microsoft says it will only offer Windows 7 Home Basic in emerging markets as an entry-point operating system on a full-size value PC.

Windows Starter Edition, which used to be its choice for emerging markets, will be available worldwide but only pre-installed by OEMs on certain kinds of hardware.

And there will be an all-dancing, all-singing Windows 7 Ultimate Edition for the rest of us that includes the security features such as BitLocker, the hard disk encryption widgetry, found in the Enterprise Edition.

Microsoft says it has yet to come up with hardware recommendations and of course it is still locked in the class action suit that resulted from the 2006 “Vista Capable” PC sales campaign that it got involved in when Vista was late to market and OEMs were afraid hardware wouldn’t move.

Consumers were allegedly misled into buying underpowered gear they thought would run the fancy new Aero user interface of the full-functioned Vista versions when it could only run the low-end Vista Home Basic.

According to some recently unsealed expert testimony for the plaintiffs, Microsoft would have to pony up between $3.9 billion and $8.52 billion for the memory and graphics cards consumers would need to run Aero. In some case it would mean complete notebook replacement.

The trial is supposed to start in April.

Microsoft also hasn’t priced Windows 7 yet.

Financial analyst Brendan Barnicle thinks Microsoft will charge around $35 for the thing on netbooks, which would effectively cannibalize the laptop market.