I would say, swap out the case and power supply. For the case, a newer bottom-PSU style helps out with system cooling quite a bit, try one of these instead
HEC Blitz Black Steel Edition ATX Mid Tower $40 w/ free shipping ($25 instant) ** excellent deal (I would pick this one, pretty sturdy case)
COOLER MASTER Elite 311 $45 w/ free shipping (one of the standard cases I use in budget builds)
The HEC Blitz has 2 fans already, so no need to purchase an extra one. That is a great deal I may also pick up one for myself just to have for my next budget build!
I highly recommend a green 80-plus unit nowadays try one of these
COOLER MASTER GX 450W RS450 $45 + $2 shipping & $10 MIR
Rosewill Green Series RG430-S12 430W $45 + free shipping ($20 instant)
CORSAIR Builder Series CX430 V2 430W $45 + $2 shipping ($5 instant and $10 MIR)
All these have good reviews from reputable sites, I would take either one of those over the one you picked since it is probably not "true" rated (would not stand up to rigorous testing to a real 500w, the three above can actually handle the stated power on the label).
If you are worried about your system needing less than a 500w psu, no worries... AMD based systems are very power efficient:
System Type: 1 physical CPU
Motherboard: Regular - Desktop
CPU Socket: Socket AM3
CPU: AMD Athlon II X3 455 3300 MHz Rana
CPU Utilization (TDP): 90% TDP
RAM: 2 Sticks DDR3 SDRAM
Video Card 1: AMD Radeon HD 6670
Regular SATA: 1 HDD
DVD-RW/DVD+RW Drive: 1 Drive
Fans
Regular: 1 Fan 80mm; 1 Fan 92mm; 1 Fan 120mm;
Keyboard and mouse: Yes
System Load: 90 %
Minimum PSU Wattage: 203 Watts
Recommended Wattage: 253 Watts
cheers