Hi Steve,
To gain any performance from relocating your Virtual Page memory, the drive it is being moved to will need to be faster than the drive Vista is installed on. Which of course you would have Vista installed on the faster one anyway though.
Usually you will just gain space by having items installed or relocated to the second drive. In some cases you can gain a bit of performance when you have some programs, like games, install on the second drive. Vista can then do whatever on it's drive while loading the program (game) on the other drive at the same time.
Hope this helps,
Shawn