We've all known that this time was coming, and now it's nearly upon us. Come April 14th Microsoft will pull the plug on free support for Windows XP (and Office 2003) and the only option available to users will be paid support, which only applies to XP Professional.
Note: If you recently bought say a netbook that runs on Windows XP then you will still be entitled to support from the OEM.
Now, security patches will still be developed and released for XP until April 2014, so is the end of free support a big deal? Well, I think that it is, given that Windows XP currently commands a 63.5% market share (I don't have breakdown data for Home vs. Professional). Being in a siltation where nearly two-thirds of all PCs out there don't have access to free support sounds to me like it has the potential to cause a lot of folks trouble.
Over the past couple of years or so I've heard from a lot of people who claim that they are going to do something once Microsoft "pulls the plug" on XP. Many of these users were loyal and entrenched XP supporters who realized that XP's reign would eventually come to an end. Some claimed that they would bite the bullet and upgrade to Vista (or maybe hold out until Windows 7). Others claimed that Mac OS X was their future, while others were tired of paying for operating systems and were going to become Linux users. Well, no matter what your plans for the future are, Microsoft is certainly in the early stages of pulling the plug on XP and if you're an XP user then it's time to at least start planning on your escape strategy.
Another factor that could drive users away from XP is that over time fewer apps will support the old OS. Right now XP enjoys pretty good support, but I expect that things will change as soon as Windows 7 is out. That, combined with no support, should drive all but the most loyal users away from XP.