GTX 470 advice

You'll probably get a few people posting what they think is the best orientation, I think your best bet is to try out various fan orientations and see what works best.

I would fill the front slots before worrying about the side, after that it depends on what needs cooling I think...I your temps are fine don't worry about it, if your GPU is hot, you might want to put an intake on the side. If your CPU is hot, a side exhaust might show improvement. Keep in mind that there is a chance that the side fan orientation may inversely affect your cpu/gpu temps, but if there is the drops in temps on one should be greater than the rise in the other, which should only be 1 or 2 degrees.

Thank you.

i'd go one front one side both as intakes as you already have 2 exhaust. but yea why not try all the possible setups and monitor temps see which is most effective then go with that

The two stock fans are exhaust.
I have the same case.
I'm not fond of the side panel, I just leave it alone.
The front is filtered, so most air coming in there will be filtered (good imo)
So put the two new fans in front on low
Set the the back and top fan on medium, they come with molex power connectors and a 3 way swithc L M H.
Medium moves a good amount of air and is fairly quiet.
At antec's site you can read the specs, cfm, rpm of stock fans in the 300 pdf , I believe.

Generally, I'd want good air intake through the front over a side intake. As notty22 mentioned, the front intakes having filters helps to keep dust bunnies from forming inside (just make sure you clean the filters now and again).

If you get sufficient front to back airflow, the GPU will have "cool" air to intake into itself anyhow. Later you can add an additional side intake if you want.

Or, as omgitzfatal suggested, you can always try both methods and see what keeps the GPU coolest. My guess is, a single 120mm side intake probably won't make a huge difference for the GTX 470 since it won't blow directly into the card anyhow.

thanks all for your input