Unless it's an Itanium, it's 32-bit. And no, it's not an Itanium.
Scrolling through the Slashdot thread shows a few related worms taking advantage of the vulnerability, some nastier than the presently-virulent one. As always, take Slashdot advice with a grain of salt, and Google until you find confirmation from something resembling a reputable source (CERT, SANS, McAffee, Norton, etc.).
As noted in some of the comments, XP has a software firewall that can be thrown up as defense from reinfection while applying the patch and trying to clean up the mess. If you aren't confident, you may want to find someone more deeply Windows-familiar to deal with the registry editing and associated hair-pulling.