I finally broke down an installed SP2 on my laptop, a bright blue Dell 300m. SP2 had been running fine on my desk top for a while, and also trouble-free on my wife's desktop, plus the laptop maker's web site endorsed it, plus all the tech columns I read (notably Ed Bott) endorsed it, so I figured, it's time.
The results are mixed. The laptop seems a little slower, especially on boot up. And one other change I made at the same time is not working out at all well. Having read all this tech advice about XP, I saw that there was a strong consensus that I shouldn't ordinarily be logged in as an 'administrator' but should be operating as a 'limited' account to prevent anything untoward taking over my PC.
Well, OK, I'm a very obedient guy when it comes to computer security (unlike most of the rest of my life), so I create a 'root' account, make it an administrator and change my usual account to 'limited' status. But now when I try to turn off the computer, both Explorer and the 'Power Meter' hang. This doesn't seem to happen when I am running solely as 'root'. All I can say is….harrumph.
Update: The indefatigable Ed Bott notes that I've run into a known Win XP problem with the 'limited' permissions identity. HARRUMPH again: they release a major service pack supposedly aimed at fixing security holes and they can't fix something like this which is a known bug — one with security implications — regarding the relationship between the MS OS and the MS Explorer programs? Come on guys!