How many still use Windows XP?

My Microsoft Security Essentials spat the dummy today over the fact that XP is no longer supported.
In a search for an antivirus, I found that even if you change to an AVP that works with XP, your computer could still be at risk, especially using Internet explorer.....however, some programs dont like Firefox.....
Anyone have a solution? Dont really want to have a complete computer revamp just now.....
Damn Microsoft...
GZ