When you need advice on deploying a new product and don't want your heart to get involved, you typically don't read marketing hype. Instead, you go with a third-party analyst's impression to help cut through the hype and give you the facts. Gartner is doing just that in saying Windows 7 is an "all but inevitable" Windows release.
Keep in mind Gartner's analysts don't say this simply because they "love" Windows 7. There is no indication in any of their comments that they've allowed their gut to motivate their opinion. Rather, they look at the current state of XP, the failure of Vista to capture the market, the benefits of Windows 7 as an OS, and frankly the drop in support from Microsoft for older Windows OSes (XP being the key). They see the handwriting on the wall for Windows 7 deployment. It will happen.
Gartner has identified five issues that enterprises should examine before they make the move to Windows 7; I've summarized them here along with my own comments:
1. Plan to be off Windows XP by 2013. If you're sweating at the thought of deploying Windows 7 in 2010 (which I'm in favor of, certainly), relax. You have until 2013 -- but Gartner says not to wait any longer than this. It isn't that XP won't be supported (it is probably going to be supported with security fixes through April 2014), but software vendors will probably give up on testing well before then. That's why Gartner says you should be XP-free come 2013.
2. Start your migration planning now. Depending on your size, your organization may need 6, 12, or even 18 months to complete a migration to Windows 7. Begin your planning today so that you aren't making a mad dash to rollout later.
3. Don't wait for Windows 7 SP1 to test and deploy. Typically the best practice with an OS is to wait for the SP1 edition before you take the OS seriously. While Windows 7 SP1 may be available by the time you decide to perform the actual rollout, you still should get started today with the current version. After all, Windows 7 is simply Vista SP3 (I don't mean that in a negative way), so you aren't looking at any major kernel rewrites here. The OS is, at its heart, the same, which is why applications that worked on Vista will work on Windows 7. Now I'm not saying they just slapped a new name on Vista -- there are enough solid improvements that it is worth the new name. For example, there are AppLocker, BranchCache, and DirectAccess, though many of these will work better with Windows Server 2008 R2 deployments.