Depends entirely on usage: an example (Score 1)

So, imagine you are using a machine with 1 GB of RAM and 2 GB of swap, following the old rule. That adds up to 3 GB of virtual memory. Now you buy your new machine, that has 4 GB of RAM. If you run it totally swapless (which is perfectly possible), and your use of it is more or less the same that the use you gave to your old machine, then why whould you even consider using swap? It's totally pointless to use the "double your RAM" method. If you don't want to go swapless, just put something like 1 GB and it should be enough. You can always add more if you need later. Reference link: http://kerneltrap.org/node/3202