First is to understand Microsoft's intentions: The company isn't producing new desktop operating systems every 18 months just to squeeze more loot of businesses like yours. Upgrading from one version to the next is painful, and Microsoft knows that. Upgrading every other version is much more doable. Microsoft knows this, too. So why do they insist on releasing a new Windows ever 18 months? Well, everyone is not using the same version. While one company using Windows 2000 is happy to wait until Longhorn, other companies using Windows NT are ready for the Windows XP upgrade.
I would never under any circumstance recommend that a business skip two versions of Windows. Doing so is too expensive (vendors stop supporting it, replacement bits are harder to get, compatibility becomes an issue, etc.). Not to mention the lost opportunity cost -- which is hard to measure, but nevertheless real. Newer versions of Windows can save companies big bucks over earlier versions and skipping two versions is tantamount to burning money.
This was first published in May 2002