i'm an openSUSE adept (as my signature tells...) but for the sake of testing KDE4 i installed openSUSE 11.2, kubuntu 10.04 LTS and fedora 13 in a virtualbox (version 3.2.0 installed from a tarball downloaded from Oracle).
1st came openSUSE 11.2, 'cuz, of course, i can install it practically eyes closed & ten fingers in my nose, tiptoeing thru the process. had to learn some about how to configure a Linux guest in VirtualBox, so it took a day until i was satisfied.
2nd was kubuntu 10.04 LTS. expected to sail thru that one, but because its install wizard takes the user for an idiot and wants to create logical partitions, i took somewhat more time to get it right; at least the user can choose to create primary partitions instead, but the default indicates that ubuntu doesn't care about manageability but, pardon my French, takes the user for a LostDOS / windoooooz idiot user.
once past that, the install went fine. next problem, but this was also a problem w/ fedora 13, when trying to install the VBoxGuestAdditions... the kernel sources are not available >:(
so what? well, it would have taken me like several dozen command lines to get around a kernel source install and i decided that it wasn't worth it (i'm running my favorite desktop on my favorite distro, remember?)
3rd was fedora 13
the install was a little smoother (wizard offers some more possibilities) but the outcomes was just as disastrous; installing the kernel sources was barely possible (only using YUM, a command line utility in conjunction with the package manager which tends to screw itself up more often then not. even after installing the kernel sources and running the VBoxGuestAdditions install script, the display topped out at a disappointing 1024x768; on a 1680x1050 screen, that seems a little toooooo conservative.
just giving debian 5.0.4 (lenny) a try.
the install wizard can be set in more or less anywhere betwee 0 to 10 in the expert mode scale & the scale of 10 allows pretty much to control everything.
so far. so good.
openSUSE is, thanks to its YaST2 (Yet another Setup Tool 2) setup tool the easiest to get working, even for an inexperienced user, because once the user accepted that YaST2 is THE (only) way to configure the system, s/he can do everything needed.
furthermore repositories can be added from www.opensuse.org
with a click on a link in your favorite browser window (that being either Konqueror or Firefox...) making the "finding a driver for my xxxx card" a lot easier then... yum what?
(yeah, yeah, i know, you can add a repository in /etc/yum.d/whatever.file, but, hey, come on... want to be user friendly?)
PS (about debian...) during the install process, the wizard allows you not to create a user but only to set a root password; but when the system starts for the 1st time... a pop-up tells you that «Root logins are not allowed.» OK?