Absolutely...
I have the Toshiba P25-S607 notebook. I am able to successfully run DDR 400Mhz SODIMM Memory in Dual Channel Mode. The laptop infact does take Dual Channel Memory and DDR 400 Mhz. I used Corsair Value Select Memory, 2 x 512MB modules. The first two modules which I received were infact not identical, so the laptop did not run them in dual channel. I used a program called Everest Home Edition to see if it was running in dual channel and DDR400 speeds. After corsair replaced them with two identical pairs with matching speeds, the laptop jumped the memory speed to DDR400 and the Bus Bandwidth increased to 128-Bit, or Dual Channel Memory. So yes, you can run it on the P25 Series.