So it was really hot in my room, so I opened my window to let the cool breeze blow in. My PC is sitting right under my window, so the winter winds are blowing straight into the back of it. It is doing an amazing job keeping my components cool. It dropped the temperature of my 4870 by 14 C. My CPU is also running really cool too.
It's cheap yet effect. I wouldn't recommend it on a rainy or humid day though.
More aboutfound perfect cooler
My rig has trouble holding an overclock on system startup when ambient temps are high, but once it's on, it's stable as a mountain no mater how hot it gets. So I usually throw open my window about 30 mins before I have to restart.
winter? middle of summer here in aus
Condensation should be something to be concerned about, when doing stuff like that.