Ideally one that is as easy as possible to install as a dual boot with XP without screwing things up with my existing XP installation.

My current disk structure is as follows:

SATA 250Gb - boot disk running XP
PATA primary 120Gb - currently partitioned NTFS but want to repartition it. Can be formatted if required - want to install Linux on a little bit of this disk
PATA secondary 85Gb - my backup disk

What's the best/easiest/safest way to do this and have a nice usable copy of Linux running?

I just downloaded the SLAX Live CD and had a play with that which looked funky, but is only a slimline Live version really

edit: looked at Slackware and dual boot looks complex. Ubuntu looks interesting...