Okay, now let's see: You can mount a 120mm in the back and in the front in the 330 case. It does help to keep HDD and overall system temperatures down quite effectively. Just be sure that the rear mounted fan does work at same or higher speed (voltage) than the front mounted fan. This way you will produce a (little) low pressure situation in the case which will ensure the hot air will get out somehow. There's no problem for fresh air to come in through small chinks in the case, it's just that these can cause noise too sometimes if they are too small, but nothing to worry about here. If you are concerned about noise from the fans and the case temperature allows it, you could run the fans at 7V (stock is 12V) or just control the value via a fan controller module which let's you choose any artificial value between 5V and 12V. Less voltage slows down the fans, which effects in lower air throughput, but then they are less noisy, sometimes down to barely audible.
For 120mm case fans I recommend you to look into Scythe S-Flex or Slip Stream series, the Blacknoise SX1 or XL1, also good are the Noctua NF-P12 - as well as Papst 4412 series is sometimes a good choice IMHO but rarely availible outside Germany, with the forementioned being as good or sometimes better I'd not give it a sweat.
I'm no fan of boxed cooling for CPU, these coolers usually aren't of high quality, only meet the minimum criteria of cooling and therefore are sometimes insufficient under high load (and moreso under your circumstands then), and some models are very noisy. Their design usually needs the fans to run at higher speeds to work properly at all, which also means they are more noisy then. So my bet is that if you do a change here you're already quite a step ahead of your problems.
If you wanna go cheap there is an Arctic Cooling Freezer 7 Pro (or also 64 Pro), if you have a little more money left you could go for either CoolerMaster HyperTX2 (probably the best buy for little money in the field atm) or Xigmatek HDT-S963, the next step up would be a Scythe Mugen or a Xigmatek HDT-S1283, the ultimate solution A Thermalright IFX-14 with a case fan from above. There is also some effects by low quality paste used for the cooler, but the quoted products shuold deliver reasonable qualified paste with them. All these coolers should require you to remove the airduct from the case due to their size, but that's not really a problem I think as they will perform better without a doubt.
Ok, hope I didn't frighten you with all the product names, but with little investments (far less than your air conditioning thing is my guess) you can get pretty much effect which will be more than sufficient even for your current situation.
Hope this helps,
PolarBear
Oh and, for anyone interested, Tomshardware.com test quite a few CPU coolers and they found out horrible differences in quality!
http://www.tomshardware.com/2008/02/20/cpu_cooler_charts_2008/
http://www.tomshardware.com/2008/02/26/cpu_cooler_charts_2008_part_2/
Unfortunately they don't list any boxed cooler set there, but my bet is that it is far down the list if not the at the bottom.