It is true we are in 21st century and god is omnipresent and  the best place to put god is our 'Mutu'. All of these answers are correct in a way. According to our Upanishad and Dharma Granthas, everything has a meaning. If one doesn't believe in these powers then; there is no rule for him/her. The person is free to make his own rules and live with them. But if one does then there are few methods of doing these things.
Now, for SexyInSari; i would like  to share few facts that i know;

Directions; Purva ;Paschim;Utter; Dakshin do carry their own meaning ; If a devotee faces north-south he/she is  directed to Karma Direction.According to our vaidik books,south is considered to be the direction of Death ( where all our karmas are located). So if u pray and do pooja facing north-south direction you will be concerned more with your mistakes, tasks, works and all material stuffs.   Facing east west helps us to gain peace as it is beyond our tasks and karma.

According to our ancient beliefs; if your are doing pooja; it surely means u want to realise god's grace, power and its only possible if your mind is peaceful and u r beyond right and wrong of karma; so it is advised to have god facing west and one doing pooja facing east.
 You can find another definition of this in terms of our bodily veins ; ida;pingala;sushumna and kundalini. It would be long to explain those; but u can read about them at:

http://www.indiadivine.org/articles/98/1/Ida-Pingala-Sushumna-and-the-Shat-Chakras/Page1.html

I hope that helps.