Maximum PC

Could not find a more appropriate thread to post in.

Anyways, I have an old P4 rig (P4HT, 3.4Ghz, stock cooler, 2GB DDR2 single channel, 400W PSU, MSI Nvidia 8600GT 256MB, win xp home SP3) that I keep outside in the shed, strictly as a media center. Now then, being from northern ontario, it gets cold, REAL COLD (-40C, around -40F). Now then, to my question.

Would it be ok to leave the computer outside, and would doing a cold boot in those temperatures damage any of the parts?

This rig lasted me two good years (my first ever custom) and has been through hell and back, playing games that aren't meant for such a low-end system (TF2, Diablo 3, SCII, and crysis actually installed, but runs like a damn slideshow on lowest settings)

So far, its only around -5C (24F) and I've left the computer on until further notice (don't wanna break the old thing)