Win XP SP1 to SP3

[Caveman]

Or does 3 include 2?

 

[nickbits]

3 includes 2 and 1

 

[RebateMonger]

Microsoft says that SP3 can be installed on PCs running XP SP1a or SP2.

Microsoft: Windows XP SP3

 

[redbeard1]

Media Center 2002 had the prerequisite of needing SP2 first.

Release Notes SP3

If you think you will have the need to ever uninstall IE7 or IE8, then you would want to remove
either of them first and then install SP3. If SP3 is installed after newer versions of IE, then the newer IE cannot be uninstalled.