The steps below are only necessary if you are hosted with GoDaddy AND you don’t already have php5 running. (It may work with other hosts but I can’t say for sure.)

To test your version of php you can run the phpinfo() command. Learn more here: http://www.web-scripts.biz/phptest.htm

If you have WordPress installed there will have been a file automatically created (providing the permissions were set properly, which they will be for GoDaddy users) called .htaccess in the root of your blog installation on the server. You may also create one with a text editor. Note that there is no actual file name for this file, just an extension. Download that file (using FTP software) to your desktop (or open it for editing in the Control Panel if you prefer). If you chose to download it, open it with a decent text editor (like TextPad, because Notepad may jumble it up) and at the very top of the file add this line: AddHandler x-httpd-php5 .php

Then save the file and re-upload. Your GoDaddy account should now be using php5.

More info: Instructions To Quickly Self-Upgrade To php5 For GoDaddy Users