Hi i was wondering if i could hook up a 120v transistor (don't know if i should use pnp or npn) to my home lights and pmw it with my arduino.
Assuming your home lights are AC then simple answer is no. Start reading here http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1230333861.
Eventually i want to be able to do this remotely, possibly by an ethernet shield.
Search these forums or Google and you will find others who have trodden this path before you.