I am assuming from your post that you only have 2 partitions????
partition #1, windows, with free space and you want to shrink it, and
partition #2, Linux, and you want to expand it?
(Note to the unwitting/noobs, I have not personnally used "gpartd" OR "partition magic" i do not make or imply any warranty to their usefulness. you have been warned)
Plan "A":
You can use partition Magic to shrink your windows partition, and then use "gpartd" to grow your Linux partition, it's available here:
http://gparted.sourceforge.net/
Plan "B":
Buy a new 40-80 gig disk, 25-50 $ at circuit city/best buy when you look for their sale price with rebates, as long as you mail the rebate form in!!!
Actually, the fastest/cheapest way might be to just by another hard drive, partition HD#2("fdisk /dev/hdb"), format it ("mkfs -t ext3 /dev/hdb1") , make a mountpoint for it ("mkdir "/t"), mount it temporarily ("mount -t ext3 /dev/hdb1 "/t") copy over the "/usr" directory("cp -parv /usr /t")
Then boot the "rescue" disk, but don't tell it to mount/find an existing installation!,
create a directory "mkdir /t",
mount your linux partition manually "mount -t ext3 /dev/hdawhatever /t",
cd into your hard drive's root partition (now mounted on "t") "cd /t" ,
delete the old "/usr" directory with "rm -rvf usr"
vi the "/t/etc/fstab" file and add an entry for for your new "/usr" partition (should look something like
this "/dev/hdb2 /usr ext3 defaults 1 0" (that will mount the primary slave's second partition on the "/usr" directory, assuming that you created and copied your ENTIRE /usr directory to this partition before starting this procedure)
reboot (you now should have a few extra gig free on your "/" partition, and your "/usr" partition will have TONS of free space on it.....okay, only if you created/formatted a big partition in "fdisk /dev/hdb" step above
(once rebooted, your Linux install will now use two partitions, one for everything on the "/" filesystem EXCEPT for the "/usr" directory, and one that contains ONLY the "/usr" directory)
Only dead fish go with the flow....
Hmmm, what did I miss?