1. the Antec 300/300 2 cases have notoriously crappy front panel connectors. otherwise they offer pretty good ventilation and the stock fans arent bad. 

2. swap out that PSU. get something from:

Seasonic
PC Power & Cooling
Enermax
Corsair (not their low-end 'Builder Series' - a few ive installed were plagued with capacitor whine). most decent Corsair PSUs are made by Seasonic.
Antec (their higher end PSUs)

do NOT scrimp on your power supply. its the most important component in your system. it protects all your other components and your house (ive watched a couple PSUs burst into flame and its not pleasant).

Ultra, Thermaltake, Cyberpower, Cooler Master, Diablotek, HEC, etc - and especially stuff like Rosewill or anything that comes packaged with a case - are all crap you need to stay away from. not to mention a 450W Seasonic would probably put out more stable watts than an "850W" cheap PSU.