if it's a dual boot for say vista / xp , I used disk director suite and it caused me headaches and I was getting MFT errors as a result
better to use gparted
http://gparted.sourceforge.net/ , and that's totally free.. using that I had no issues.. I did the re-size in gparted.. BUT when I was using the upgrade vista, I formatted the new partition in xp.
if you put vista on you'll get a new boot manager also
there is a vista boot program also which is very handy,
http://www.vistabootpro.org/ this is a handy guide
http://apcmag.com/how_to_dualboot_vista_with_xp__stepbystep_guide_with_screenshots.htm there is a drop box at the top, and you can change the choice of OS etc
but yep backing up before hand is always a good idea.
disclaimer : you do the above at your own risk
edit : the only thing I will say, having a laptop also.. I stuck to one OS on it down to the drive size, with a desktop and far bigger drives , it's not a big issue. You might find a hidden recovery partition on the drive, leave that be, just in case for the future.
post edited by Fog - 2008/12/23 05:40:52