Starting April 8, 2014 Microsoft will no longer support Windows XP.
1) Microsoft will not issue security updates. This may leave your computer vulnerable to attacks, virus's etc...
2) Internet Explorer will no longer be updated. If you use this web browser on XP your computer may be vulnerable.
3) Since your computer will be vulnerable it will also leave the files on your computer vulnerable.
3) As support for XP ends many companies and new software will not support XP.
Options
Most XP computers can have Windows 7 installed on them, however Windows 8 will not be compatible with most XP computers.
If you choose to install Windows 7 all your files, software, hard drives will be wiped. It will be like a new computer.
It is important to back up your documents to a reliable media such as a USB Flash Drive or External Hard Drive.
To make a copy of the file you can right click and select copy, than right click where you want to copy it to and select paste.
Some file locations to consider backing up...
My Documents
My Pictures
My Videos
My Music
Downloads
You can also create a backup of your bookmarks from your web browser.
In Firefox
Select Bookmarks from the menu bar.
Select Unsorted bookmarks.
Import and backup, backup
Save your bookmarks to an external device.
In Chrome
Click the three bars in the top right hand side of your browser
Select Bookmarks.
Select Bookmark Manager.
Click Organize.
Select Export bookmarks.
Save your bookmarks to an external device.
In Internet Explorer
Click on the star in the upper right hand corner.
Click the down arrow next to add to favorites.
Select Import and Export.
Export to a file.
Select Favorites.
Save your bookmarks to an external device.