I only used Ubuntu briefly myself, theres nothing wrong with it, I just happen to prefer portage to apt-get. In terms of the partitioning I have to admit I didnt realise you used a windows based program to get that output. Was quite obvious really I dont know why I didnt make the connection
In terms of your backup needs, if you have a home network, or even a spare PCthat you can network to your main one, you could do what I do. I have a cron Job running that every 2 nights backs up my home directory to a network share.
Mandrake 10.0 was indeed a pretty good distribution, when i originally started using Linux Mandrake is what i started on, although it was far earlier than version 10.0.
Whether Ubuntu will be good for you is dependant on how you like your systems to be, as I say I prefer portage to apt-get, so I preferred Gentoo, but then I do like to be in control so perhaps its the installation method that attracted me to Gentoo. The good thing about Ubuntu is that you get a live CD as well, so it means you cna put that in first and check you like it. Not knowing more about your needs I dont know which distro to recommend, although if you are interested in SUSE then the boxed version is worth buying. It may be that you can get a 64-bit version of SuSE OSS on the net, although I would guess its quite well hidden.