the above (apparently, from the description) doesn't do partition resizing, although apparently this does:
http://www.zeleps.com/
Beware of your (soft) RAID-1 mirror. Linux will probably/possibly treat the controller as a regular sata controller and see the disks individually. There will be ways to control this behaviour but at least keep an eye out to see if the Ubuntu setup wizard sees two individual disks or one virtual disk (the mirror). There are various ways to deal with RAID in Linux, and I believe dmraid can read the sata softraid metadata and work with that, but you may need to be vigilant and careful. I haven't installed Linux on an existing softraid mirror like this so I could be wrong, it's just what I've read in the past.
I'd start by confirming what chipset your softraid uses (Highpoint HPTxxx, Silicon Image 3xxx, Intel ICHxxx or whatever) and googling from there before you start.
Best bet would be to spend £40 on a 120gb HDD and install it on there.