Just keep an eye on your temperatures when you get your computer. You can monitor temps with Speedfan
and you can stress your system with Prime95
If your CPU stays below 60°C and your system below 50°C during the torture test, I'd say don't worry about the extra fan. In the event you find you do need an intake fan, be sure to get a good quality, quiet, 3-pin fan since you are more prone to hear/notice a front fan. Look at the dBa ratings of fans and try to stay below 20 dBa.