Not sure if I'm reading you right here: installing VB is quite painless on Kubuntu. Getting USB to work is where the pain comes in (and as I understand it it's painful on all versions of Ubunutu).
I know the first time installed Virtualbox i had endless hassles trying to get USB working now I do it in this order on Mandriva.
1.) Installed OSE version from the repo's this makes sure i get all the correct kernel requirements otherwise i get confused

2.) run # /etc/ini.d/ ./vboxdrv setup
3.) Reboot my linux machine.
4.) Make sure VB is working
4.) Remove the OSE version (only that leave all the kernel bits)
5.) Install the package from sun's site.
6.) Reboot laptop.
7.) Start VB and load my virtual windoze drive.
8.) Install guest additions
9.) Select my shared folder and activate USB devices.
I have one "windows harddrive" (.VDI ) that I use on all my laptops so I don't have to activate windows each time i install VB.
Tried the same procedure on Opensuse yesterday and it worked, I suppose looking back at my list now it is rather long winded and I am sure I could probably skip a few steps but it always works that way so will stick to it.