Lots of businesses and regular folks still use XP, and only upgrade when they buy a new box. The problem is that XP is unsafe on the internet, and in a year or so will become TOTALLY unsafe because MS will stop supporting it. So it's time to move on.
The good news is that your old machine can work faster with a different operating system. If you want the same familiar interface but a modern, safe OS underneath, install Zorin or Mint. I've been running Mint for 2 years at home and work, and never looked back.
Here's my never-fail recipe:
Back up your data files on the cloud, external hard drive, or DVDs.
Go to Distrowatch, hit Search in the upper corner, and type in the search box whatever preferences you have (like, old computer, scientific, multimedia, etc). Check out some of the resulting distros and see which best suits your situation. I recommend Mint for the beginner; Ubuntu has a wierd menu, but lots of good documentation (mostly works for Mint too). Zorin mimics the look of Windows, if you prefer. Go to the distro's website, download the ISO and burn to a disk or flash drive.
If you are going to dual boot with Windows, run a defrag, clean up your files with CCleaner or equivalent, take out the trash you don't need, uninstall all the crapware and apps you never use. Search for "dual boot tutorial" and read a few of them, too long to put here. There are some great YouTube videos. (If you are erasing Windows, never mind the dual boot stuff; installing one OS is way simpler.)
Boot off the disk and see if the Linux distro runs great on your machine, and sees all your hardware, like camera, sound, etc. Then hit the "Install" button on your desktop. You'll need to make up a username and password. Then if you are dual booting, you need to "install alongside Windows", as per the tutorials. Otherwise choose "replace Windows". Then about 10-20 minutes later, you'll be ready to get back to work after you copy all your data files back in.
You will then be free. No windows, no gates.