Excellent! An SSD and stock Gnome 3 Debian in my X61s (2Gb RAM) with its Atheros wifi card goes very well, so I'm hardly surprised that your machines work well

Excellent! An SSD and stock Gnome 3 Debian in my X61s (2Gb RAM) with its Atheros wifi card goes very well, so I'm hardly surprised that your machines work well with a less demanding desktop environment and it is good that you find them of use. Care to share the output of pstree -l -A from a fresh session? That would tell us what processes are running by default (cups&c).