Let me open up by saying though that if you're using Vista-you poor, poor person-yes, you should migrate to Windows 7. After all, Windows 7 is really just Vista without the warts. Otherwise, no, I don't see any compelling reason to switch.
I say this as someone who's also been running Windows 7 since the late betas and I'm currently running the RTM (release to manufacturing) version. I like Windows 7, but if you were to ask me what the big feature, the 'wow' that would make you want to go to the trouble of moving to Windows 7, I'd be left without anything to say. Heck, look at Gralla list, number one on the list is the new taskbar. Microsoft wants me to spend big bucks for a new taskbar!?
OK, on with the list.
1) Windows 7 still has all the security of a drunken teenager in a sports car. From Windows for Workgroups and NT 3 until today, Windows is a security joke. It used to be that running Windows just put your head into the noose. Now, millions of lazy Windows users are the reason why the Internet is a mess. If you already do all the right things to keep XP running safely, you're not going to get any safer by buying Windows 7.
2) Windows 7, no matter how you buy it, is expensive. Does your budget have the extra cash to buy a new and improved taskbar!?
3) Upgrading from XP to Windows 7 will require that you do a clean install. That means everything on your hard disk gets vaporized during the 'upgrade." Vista users have it easier. So long as they're moving from equivalent version to equivalent version or to Windows 7 Ultimate they can update without needing to rebuild their systems.
There are lots of ways, like Microsoft's own Windows Easy Transfer and I'm sure there will be many more, to migrate your data from your old system to your new one, but all of them take work. If you have a business with dozens to tens-of-thousands of Windows PCs you can count on a honking, huge upgrade bill.
4) Did you notice what I didn't say above? I didn't mention transferring your old programs and device drivers from XP to Windows 7. For that, Easy Transfer and most of the first generation of migration programs are of no help at all. You'll need to reinstall your old programs and device drivers. Then, you'll need to update all those programs and drivers. Doesn't that sound like fun? Doesn't that sound like hour after hour per PC of migration work?
5) XP already works. I can tell you chapter and verse on why you'd be better off running desktop Linux or put a Mac on your desk. Most of you though are happy running XP. If that's you, I'll be darned if I can think of a single, significant change that you'll get from running Windows 7 instead of XP.
6) If you're an XP user you'll need to learn a new user interface. Parri Munsell, Microsoft's Director of Consumer Product Management for Windows, has been fond of saying, "Our goal was to make the UI (user interface) in Windows 7 much easier to navigate." OK, I'd agree. It is a bit better.
But, I'm someone who switches operating system interfaces as often as most of you go out to get a pizza. I asked some friends who were XP stalwarts what they thought about the interface. They all thought it was pretty, but, they also all found it annoying to work with since they had to re-learn how to do XP basics. Vista users will have it easier, but XP users can expect to have a learning curve with the new UI.
And, once more, I find myself asking, "Is there anything here that's really a solid improvement on XP?" Or, to get brass tacks, if I'm a CFO or CIO, I want to know what I'm going to get out of re-training people to the new interface and I'm left thinking there's really nothing game-changing about the Windows 7 UI.
7) Finally, if you have an older PC, forget about it. I know there are people who swear that Windows 7 will run on low-powered PCs. Yeah, right. I've used Windows 7 on netbooks. It wasn't pretty. Windows 7 Starter Edition? Microsoft won't sell it to you.
Bottom line. If you want something that's really better than XP, and you're willing to go to the trouble and expense of moving from one platform to another, you'll get real improvements like better security and low up-front costs, from a desktop Linux like SLED (SUSE Linux Enterprise Desktop) 11 or Ubuntu 9.04. Windows 7 is certainly better than Vista, but XP... not so much.