No problem if you are running a relatively recent kernel: you should be

able to use both a swap-partition (for good performance) and a swap-file

(for the overflow that won't fit into the partition) at the same time.

Just do:
 - create the swapfile (needs to be done only once):
        # dd if=/dev/zero of=swapfile bs=1024 count=8192

        # mkswap swapfile 8192
 - enable swapping (usually at bootup):
        # swapon /dev/hdXX

        # swapon swapfile
Note that you had better enable the partition first - linux doesn't do

any clever swap-space striping or similar, but instead uses up the

swap-pages in the order they were installed.  So enabling the partition

first means that it gets "preferred status", which is generally what you

want (as it's noticeably faster to swap to a partition). 
                Linus