The vast majority of Windows hosting plans offer PHP support as well as a MySQL database installation. This means that you can develop a PHP website or transfer your existing PHP website to this Windows hosting plan.

If you plan on developing a PHP website using a MySQL database then it makes sense that you purchase a Linux hosting plan because it is slightly cheaper than a Windows plan, thus saving you money.

However, if you plan on developing multiple websites on a single plan, some of which are developed in ASP and others which utilize PHP, then purchasing a Windows hosting plan may be a valid option.

With plans being as cheap as they are today, I tend to have a one Windows hosting plan and a separate Linux hosting plan for the various websites I like to tinker with.