There is no way that you can access anything on any un-powered computer.
What you can do is remove the hard drive from that computer and install it on another. You can install a laptop drive on any desktop. You may not have the place and connector available to connect it in another laptop. In that case, you should mount it in an external USB or eSATA case and connect to an USB or eSATA connector.
You CAN NOT install it as the boot or system drive in the other computer. If you try, the OS will start to load, but then it will fail due to different hardwares, drivers and configuration isues.
Once it's connected and the other computer turned on, all of it's content will be totaly accessible. The passwords may be hard to access as they are normaly encrypted.
Electro
April 2012