I have no idea what is going on with WinXP Firefox 5.0 users not being able to update to 5.0.1, either automatically or manually. I have two separate version of Firefox 5.0 installed, each with their own separate Profiles; one with automatic updates and the other with all updates turned off, and I haven't been able to get Firefox 5.0 to update to 5.0.1 - have tried 3 times on the "manual" installation with the "Check for Updates" button. I'm gonna see if the automatic update happens this evening, 24 hours after the first time I opened the the automatic update version and let sit idle for like 3 hours (I don't use that version everyday or for much of anything) to see if it would get the update by it self.

I went to download 5.0.1 and saved it, then run from the installer and now I am on 5.0.1. I saw some Windows 7 users have 5.0.1 installed already, I don't know if they use the UPDATES option or a fresh Firefox installation. Maybe Firefox forgot about Windows XP users, or it takes sometime for UPDATES to get 5.0.1.

I went to look at the Release notes of 5.0.1 and found that this "update" only benefits those using MAC OS. Maybe that's why it's not in Windows Firefox Update.

After I updated to 5.0.1, I don't see any changes, except a couple of add-ons which are not compatible which are easy to fix by configuring its install.rdf file.

So for those Windows users, as I can tell, it's not important to update to 5.0.1. You can wait for version 6 if you prefer.

http://www.mozilla.com/en-US/firefox/5.0.1/releasenotes/