OK, so I found the "df" and the "du" commands..... :p
Here's the output from "df";
Filesystem 512-blocks Used Avail Capacity Mounted on
/dev/disk0s1 545856 540384 16 100% /
devfs 36 36 0 100% /dev
/dev/disk0s2 15244736 320536 14924200 2% /private/var
So on /dev/disk0s1, which is where I assume Applications get installed by default, i seem to have zero free space (almost) which would tie in with what BossTool reported. Yet I can still install more apps in installer so where are they going?
So what is iTunes telling me then? And which is correct; 7.6 or 7.4.2?