I subscribe to automatic updates and haven't had any recently, so have I got SP3 or not? Is this limited to the US at the moment?
Click on "control panel>system" and on the general tab, it should list the version.
I followed the "avoid it" advice, and my desktop machine is fine without it.
My new laptop came with it, and with some strange habits. I uninstalled it, and the laptop's now fine.
I like playing with Beta (and even Alpha) software, but when it comes to the basic operating system, I stick with "if it ain't broke, don't fix it".
While this approach will be fine for a while, sooner or later in the (extended) life of XP, there will probably come a time when SP3 needs to be installed for continued support.