I dumped XP a while back. I'm on a collection of old machines running Debian Linux which runs faster than XP does on the same hardware - Generally.
I also have two Macs, one running Lion, another on Mavericks.
The Windows machines are either on Windows 7 or the cringeworthy Windows 8.1. Windows 8.1 does "seem" to run well, but the effort I have to put into making sure that the "Ugly Block Land" of the Start Screen has everything I want, and none of the chaff of their live tiles has turned me off of Windows. I avoid using Windows 8.1 as a result.
There are also the security and privacy questions that I have about Windows in general. Any software that "phones home" for updates is by definition a risk - whether it is a miniscule one or not.
The computer I use the most is a Windows 7 laptop, I'm comfortable there and will remain that way until I am forced off of Windows 7 for a business reason.
All that having been said, there are some folks who I Support/Chat/Help/Consult for (and so forth) that still have Windows XP computers that run every day.
Please upgrade those now.
Extended Support for Windows XP will be ending April 8, 2014.
Windows Update will cease to function.
Internet Explorer will no longer be updated and become even more abysmal to use in time.
You will be forced to use Chrome or Firefox for a "modern" browser.
Now the latest announcement - if you use Microsoft Security Essentials for your virus protection, you will no longer be able to get updates.
Seeing that I get an update on a daily or more than once a day basis on my virus signatures on Windows 7, that is a significant issue.
The XP user will have to pay for a virus protection program - and it is a big market with many names. But by the time you get that virus, you won't be able to save your data.
I've had one virus hit this machine in the time I have used it - one year. While that clobbered my computer, I was able to restore from a week old backup. All my data is stored either on a SDHC chip or on a network - so I was safe. The hard drive on the machine is not for "permanent storage".
Do you have that kind of regimen?
I have a good friend and neighbor who clicked on a link in an email and immediately knew he had a Cryptolocker Virus screaming at him that if he didn't pay 300 bucks for a ransom, his info would be passed to the FBI. While that threat is bogus, it shows how easy it is to get a virus now. For XP Users on April 8, 2014, it will get easier since they are already writing viruses to take advantage of back doors and other exploits. At current 30 percent of US Computer Users run Windows XP.
At any rate, if you are one of those folks who can't afford to pay the 100 Dollars US for a copy of Windows 7 or 8, I strongly recommend looking into a free copy of Debian or Ubuntu Linux. Since they run Firefox as a browser as the default, you'll be fine.
After all, why spend 100 for an operating system when a new computer runs around 200 dollars for a "beater". If someone is running XP then their computing needs are a bit more modest than someone who needs a top of the line beast.