put this in your /etc/fstab - but replace /dev/hda4 for where your swap-partition is:
/dev/hda4 none swap sw 0 0
just saw that gilead
was a bit quicker...
should work eighter way...
first is: which partition
second is: where it is mounted to (which directory...) since there is none it says so...
third: type of filesystem - swap in this case
fourth is: the mount-options - sw here
see: man fstab