I'm not sure as far as Woody is concerned, but I know that in Slackware, you can mount to root if you like.
I would try it - and see what happens.
Worst case - make another logical dir, and move all of your media/downloads there - and save the space on your root dir.
There is one other thing that you may try, but it can be hairy.
If you prefer, you can move all of your files in a large dir to the other, unused partition, and then, delete that tree from / - and specify in your /etc/fstab that you wish to mount that partition as that specified tree. NOTE you must be root.
This example would be with /usr (a HUGE dir) As follows:
user@woody# mkdir /extradrive
user@woody# cp -fR /usr /extradrive/
user@woody# nano -w /etc/fstab
(this is my /etc/fstab - yours may differ)
/dev/hdb5 swap swap defaults 0 0
/dev/hdb6 / reiserfs defaults 1 1
/dev/hdb1 /boot ext2 defaults 1 2
/dev/cdrom /mnt/cdrom iso9660 noauto,owner,ro 0 0
/dev/fd0 /mnt/floppy auto noauto,owner 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
proc /proc proc defaults 0 0
add the following entry to yours:
/dev/hda3 /usr ext2/3/reiserfs defaults 1 2
***NOTE - be sure to change /ext2/3/resierfs to the correct format of /dev/hda3
user@woody# mv /usr /usrold
user@woody# mkdir /usr
Reboot, and hopefully, all will be well.
If it is - you can rm -fR /usrold
If not, you can boot into single user mode - and rename /usrold back to /usr.