Thanks to all, for all the tips and links already!
In short, no defrag for the moment, until I get rid of another 1.5Gb of files, to have at least 15% space.
Disk Clean is routine here, already... it's astonishing how 'temp' garbage accumulates very quickly.
Oh, and a dumb question... how do I start XP in Safe mode? I knew how to for Win95 and 98, but not for XP.
CJ
PS It's not that I'm a newbie... I've been through the whole gamut from ISIS-II through all the DOSes, with sidesteps into Unix et al, but the last few years, with XP, I've had so few problems (relatively), that I've had no reason to delve into the innards in the same way.