Hi,
I have 80GB on my laptop. I have 3 OS, slackware main, slackware testing (testing the -current), and windows XP.
Windows XP - 10GB - previously 15GB but give 5GB to testing (OS, ms office, browsers, bluetooth app, plant vs zombie
, etc)
Slackware Testing - 5GB (slackware -current except KDE and KDEi)
Swap partition - 3GB
Slackware main - the rest (cool stuff here
)