I'm replacing most of the gubbinses inside my computer, including a switch to X86-64, and so i thought this would also be a good time to try out a new distro, i want to give Kubuntu a shot.

The problem is that there's about 70Gb of various things in my home dir/partition (i'm the sole user) that i really don't want to lose, and i can't find enough HDDs to make the room to back it up (i've already got backups of what's most important).

If I try to get Kubuntu to just mount that partition as the new home directory, will all the apps that have installed themselves in there still work? Also, how could i transfer some of the configs from old to new? Like the look and feel of KDE, and mail accounts from KMail?

Cheers!

If /home is on a seperate partition, then there is nothing much to worry about. Everything will be preserved as long as you don't format /home during the installation of a new distro. Kubuntu should use your KDE settings although you may have to reinstall any third party themes.