I realised after my previous post I realised that it would be worthwhile talking about adding a new partitition.
The first thing you need - or I assume - is that you have a separate hard-drive which is not active (mounted) or can be unmounts using the standard umount command.
We assume the device is sdc (it could be sdb, sda, hda1 etc..).
We had a problem on one of the servers which I help administer. Every now and again RAM usage would max out and SWAP would then be used - this would sometimes max out and bye bye server, normally this happened for only a few seconds and all was fine - however if it lasted more then when SWAP ran out - the server ground to a halt and needed a manual restart.
The server in question is quite busy - but only had 512Meg of RAM (this has since been rectified) historically as it wasn't that busy at first several years ago has slowly grown as websites on it have grown in popularity and databases have grown.
So an immediate fix was required