That depends. The Wallstreet used PC66 SODIMM, where the Pismo used PC100 SODIMM. So, if it was the ram that shipped with the Wallstreet, it will not function. However, if it was ram that was added afterward, it may function. Remove the ram, and look at the tiny sticker on the chip. It should say either PC100 or PC66. PC100 will work in the Pismo, PC66 will not.