oi... I'd say yes to a fridge, no to a freezer... you COULD use a freezer, if you never opened it again, which its what adds the moisture. I'd say you'd be better off running a liquid cooling system as previously suggested, using anti-freeze and water like a car and running a coolant tube (coiled to make it stay longer) through a freezer to cool the CPU for OC'ing. beneifit here is it won't be open to the moisture, and it will be super cold.... if you do this, make sure your computer is warmed up for a while so the system levels off as far as cooling capacity (means you can't change and test and go with it, or you could get it too hot w/ catastrophic failure during a longer session)
if you go to try the coil method, use 3 or 4 small diameter tubes, which will greatly increase your surface contact and cooling ability (slower flow with more surcface area, a radiator concept, except the coils could be put under a tray and would not take up as much room)
I don't think the other PC components would hold up to being in that enviroment, the rapid cooling off of the parts could be problematic in the long run, not to mention introducing moisture (hehe and fogging the CD's) to use the CD drives. unless you use external which is kinda slow for gaming....