I spilled coffee on my Dell Inspiron 154...

You might be able to find a cheap replacement palm rest (which includes the touch pad) on E-Bay or similar site. Just search your model number.

As far as replacing it yourself, I recommend having someone that works on computers regularly doing it, unless you are completely comfortable working inside the laptop. If you are (and you take all necessary precautions), here is the Service Manual from Dell which includes disassembly instructions for the palm rest.

http://support.dell.com/support/edocs/systems/ins1545/en/SM/index.htm

try to take out the keyboard, then it gotta be something for the touchpad