hey dude, you should try and understand that when someone gives you advice they're trying to help you.

keeko is right, light from a window is unreliable, in duration as well as in intensity so it is unlikely you will achieve any real results, you'll get something, just not much.

heres a link to a thread that you should read from beginning to end, after which you will know way more about how to grow ganja, cheaply.
http://boards.cannabis.com/grow-log/...-grow-log.html

and try to relax man, don't take advice from everyone obviously, but if you hang around here a while and read the threads, you'll quickly see who to listen to and who to ignore. (check out thier reputation, not a guarantee of good advice, but someone with as many rep points as keeko probably knows what he's talking about)

anyway, good luck with your little grow