40Mb is perfectly fine. I managed to squeeze a huge amount of stuff on my old 40Mb drive. I now have a 40Gb drive, but my 3.9 partition uses up only 18Mb (my main 3.1 partition uses up about 75Mb, but has loads of unnecessary extra stuff).
Besides the Workbench, here's a list of some of the stuff I squeezed on my old 40Mb drive (40 megabytes, NOT gigabytes)
Miami MUI
YAM IBrowse
Newicons VisualPrefs
MagicMenu TitleShadow
PowerSnap Checkmate
ModePro Scout
SnoopDOS GoldED
rainbow SimpleFind3
ScreenShell DrivePrefs
env-handler MrCopper
NISClock WindowToFront
Iconify Voodoo-X
WizArc Hex
Beast Music Synth/Swinth/Synth.sid
Klidex Checkmate
Visage TotalCalc
PageLiner Zoom
VideoPoker AddTools
BorderBlank SystemPatch
Skick AHI
RunFromWB VersionWB
Clip DaysBetween
DoIcon ShowIcon
JPG2DCTV Iconian
VirusZ CompareDirs
EaglePlayer & Misc Music Misc Good Mods
PPaint Arexx Shell
SampleZ SongPlayer
Shadow of the Beast Faery Tale
Zeewolf II Speedball 2
Ruff'N'Tumble Fractal
ABCDir!
I also had all my "eye-candy" stuff and still had about 6Mb left for internet cache. You just have to keep what's necessary and not fill up on crap.
Edit: my list appears tabbed nicely in two columns when I edit the post, but is squashed together when displayed in the page! Just try to imagine it as two columns ;-)
If you don't need 3.9, don't get it. It's not worth it.
