First Q:
I've got

Rockford:
2 x P3D412
T1500-1bd

Im from Ontario Canada, and its getting pretty cold, do i bring my set up in for the winter?

Second Q:

Ive got a Sound Blaster X-Fi Extreme gamer sound car in my pc, ive heard its possible to rig up subs to the pc using a pc power supply, can someone recommend one for my setup. I'm not sure what i should be considering

Thanks for your time.

 

I have never had to take a system out for the winter. Just when it is cold wait for a few minutes to let everything warm up a bit before you crank it up.
Nick

 

Start here:
http://www.mp3car.com/vbulletin/faq-emporium/51060-faq-power-supplies-explained-part-1-a.html

 

As mentioned already, leave everything in the car and just take it easy on the volume until things warm up.
Sure it's possible but what exactly do you want to accomplish? Do you want to move your car's subs into the house for the winter and connect them to your PC? If so the best way to do this is to get a hold of a large 12V power supply. A PC supply will work but it's a bit on the small side for your amp.

I have done this before but I used an old receiver for an amp. I had a stand-alone electronic crossover which took care of the low pass filtering. This way I only needed a 12volt "wall wart" adapter to power the crossover. It was an old Phoenix Gold MX2, there are many similar units out there and they aren't expensive.