Advantages Disadvantages PS3-XBOX360

I am thinking right now about the possible purchase of a next gen console: PS3 or Xbox360.
After some research on the NET I more or less managed to have positive and negative points of both consoles, but I have the opinions of people from the forum have either (or both you never know 

XBOX 360:

• the least noisy, unreliable (at least initially), optional HD DVD, HD DVD (the blu ray now), Xbox Live paying (that is also how many?)
• the most: many hits (GoW, Halo 2 and I forget ...), graphics rendering

PS3:

• the least: many heats, online game not terrible (lags ...), incompatible with many PS2 games?
• the more silent, free online game, blu ray, the online store. graphics rendering too (I just see a demo> Devil May Cry is really cannon.

Another issue I want Question of size hard drive, is it really important to have a large hard drive on the PS3? I understand that now only the 40GB model was sold and that Sony allows changing the hard drive (there is a door at the rear that provides access to the disk without opening the console). 
and the 360? What about the hard drive? 
And last important issue in terms of power consumption, What? the sticks are they strong consumer battery?
thank you for your responses