How can you Reduce Disk Swapping in Linux?

A member of the voiceferous Clan Anonymous Coward asks: "I am finding that on my 64meg box that Linux is using the swap file even though it looks like there is plenty of RAM, but it is used by the disk(?) cache. For example, 4.8M of swap is used when the disk cache is 20M. What can be tuned to reduce the disk cache size? Sample /proc/meminfo info follows: total:64569344 used:57200640 free:7368704 shared:32337920 buffers:3235840 cached:20496384 used-swap:4837376"