Spinning beach ball of insanity

[Edward Arrowsmith]

Friend has a 1.25 G4 768 RAM. Under 10.3.8 suffered interminable 
spinning beach ball. Installed 10.4.2, spinning beach ball better but 
still occurs when switching between apps. SBB only appears in top right 
corner near menu bar. Switched RAM, no joy. Force quit won't work, must 
turn off at wall then restart. Runs OK until need to switch apps.

Friend is about to lose abundant sanity. Please help!