Jz1397-4, a Ramdisk is when you use part of your RAM as hard drive space. It is actually much much faster than any hard drive, but is limited in space to the amount of RAM you have. What you were talking about is the complete opposite, or virtual memory, when your computer uses some of your hard drive space for RAM.
Empiretank - With 256 megs of RAM its probably best if you dont even bother with a RAM disk. A RAM disk can and will increase your performance significantly if used properly, but, with your 256, using it for anything other than internet temp files is not a good idea. It doesnt hurt to give it a shot, take it for a spin and see if you like it or notice a performance increase.