XP is already more than 10 years old, and has passed it's expiry date. Microsoft keeps extending XP support (currently until 2014), due to pressure from the corporates that cannot move on to a newer OS for whatever reason.
I liked XP and was still content using it last year until I started finding more and more of the newer applications & software upgrades that don't support XP anymore. The same can be said for new hardware.
Even Google & Android app developers are not supporting the older versions (vers 1,5 /1.6) of Android anymore.