Windows updating to sp2 and can't dl updates for sp1

Two parter, please help>

Should I update immdiately or go with a clean install later for xp sp2. I already updated from windows 98 originally (XP was an update not a clean install) and I am not sure how this would affect my system. Would updating from what was originally an win98 FE to xp to xp1 to xp2 cause more system instability? I was eventually going to just wipe and start fresh but if it doesn't cause instability then good! Also is there anything else that should prevent me from updating due to my system's condition.


P.s. the updating wasn't my first choice I just wanted to get updates to windows opertating system but keep getting a unsuccessful update of windows message. I have sp2 blocker installed is this why I can't update or is this not the cause?

 

“Blocker” has Expired April 12, 2005
The "blocker" mechanism that temporarily disabled the delivery of Windows XP Service Pack 2 (SP2) through Windows Update and Automatic Updates has expired and is no longer available.

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Have you done any of this yet?