As Derango says, don't disable the swap file. Many programs require a swap file to be present, even if they don't actually use it.
Windows XP's memory management is very good and doesn't usually use the swap file unless you really run out of RAM. The default setting that Windows uses is to create a swap file that is 1.5x the size of your system RAM, called pagefile.sys. You are free to reduce the size of this file if you wish.
I personally have the thing set to an initial size of 200MB, and I very rarely hit the swap file with 512MB of RAM.