It will work fine on XP. When you download it if you want to try the new Orange Firefox Button(only shown by default in Vista and 7) right click on toolbar space and uncheck Menu Bar. You can toggle between the two.

I would recommend you read this -

http://www.mozilla.com/en-US/firefox/features/

It will help if you get rid of Ask - courtesy Xircal

https://support.mozilla.com/en-US/questions/831158

Thanks alan_r, at least now it will stop popping up to update. I will let it update to 4 and see what happens.I will do what you recommended. I do appreciate the reply, nice to know there are people out there with help.thanks again. littleone

Very happy to help, especially for such a pleasant thank you. Alan

Allen,you are so nice. I did update to version 4.0.1,and so far it's working great,I lost a few add on's,at least until they become available,no big deal there. Thankful & Happy Firefox user, littleone