With the price of Windows 7 topping out at US$320, Microsoft will be handing shoppers less cash at the end of its "I'm a PC" commercials. Price advantages of Windows-laptops over those from Apple evaporated further today as Microsoft's latest operating system hit store shelves and OEM factories.

In typical Microsoft fashion, there are six versions of Windows 7, something for everyone at every price point. All but the Starter Edition support 32- and 64-bit architectures. At $320 are the feature-identical Ultimate and Enterprise Editions. Both are available at retail and pre-installed through OEMs; volume pricing is available for Enterprise. Here's a question for Microsoft: If they're identical in every way, why offer two? The company says it's targeting one at corporations and the other at hobbyists. And?

Even more puzzling is the way Microsoft divided features of its Home Premium ($200) and Professional Editions, (both also available at retail or pre-installed). Home Premium limits system to RAM 16GB, while Pro permits up to 192GB (as do Ultimate and Enterprise). Home Premium also is limited to a single CPU (others max out at two), can't back up to a network drive or encrypt files, and lacks an XP Mode, which runs a virtual instance of Windows XP for apps not yet ready for Windows 7. Today's "home" users are a pretty sophisticated bunch; I don't think Microsoft gives them enough credit.

Windows 7 is still cheaper than Vista, which maxed out at $399. And if you're upgrading from a prior Windows version, the cost is about $100 cheaper. Also, if you're moving from XP, you'll have no choice but to do a clean install. Which means reinstalling all your apps, plug-ins, drivers and data. This is a serious bummer. Vista users can choose between an upgrade path or clean install. Either way, support will cost you extra.

Microsoft offers a pair of tools to help you determine compatibility with Windows 7 of your system and installed applications. For a full feature breakdown, refer to Wikipedia's Windows 7 feature comparison chart.