A) a gfx only needs a fan if it's a high heatoutput core
you can use an FX 5200 which only requires passive cooling, and introduces less heat due to that, fans don't increase performance, if the gfx card has a fan on it, than it needs it, if it doesn't, than it probably does not need a fan (but if your OC'ing a gfx card that came w/o a fan, i'd suggest getting it a new cooler with a fan)
B) a 300W PSU is WEAK, and under the requirements of most graphics cards, i would suggest 450W or more from aa reputable company, meaning 24A on the 12v line or better, or dual 12v lines at around 15-16A each
C) i suggest 2 case fans, in any configuration, as long as they aren't right by each other (if one is in a door and the other is in the back, that is fine, if their stacked, you need a fan away from them, to create air flow)
D) a CPU fan isn't just something to over-look, you should have a quality HSF, not the one that comes with it
SO HERE IS MY SUGGESTION BOX FOR CASE/PSU BUYING:
1. The case must meet the ATX form factor requirement, even if you have a Micro-ATX board, as a full ATX case allows a larger area for heat to dissipate
2. The case must have at least 2 fan mounts (if it includes fans that is better) and have fans in those mounts, they must not be on top of each other, they must be in different places to either cooling critical parts (i.e. a tunnel right over the CPU) or at oppsoite sides to create air flow
3. The case must have a front fan, and a rear fan
4. The fans must be of high quality, meaning 30 CFM or better
5. The Power Supply must meet the ATX requirement for your hardware (either 20-pin or 24-pin) and must supply in the range of 24A on the 12v Rail for Pentium 4 and Athlon64, and in the range of 22A or more for AthlonXP and Sempron
6. The power supply must come from a good manufacturer, such as Enermax, OCZ, Antec, TTGI Superflower, PC Power & Cooling, Fortron Source Power, Sparkle Power, Zippy/EMACs
7. The power supply must have 2 FANS! no quesions asked (99% of all of the above's PSU's have 2 fans...if it's a micro-ATX PSU for a lower power or SFF system, 1 fan is fine...BUT the rest of the system must be low end/well cooled)
8. the PSU fan mustn't do most of the cooling, meaning a rear exhaust fan is required
if the case meets most of that
go for it
also
don't buy Case/PSU bundles, the included PSU's ALWAYS suck (if you bought a good case and a good PSU in a bundle (say a Xaser V and an Antec NeoPower) it'd cost like $300+)
and as an afternote
Thermaltake's PSU's are OK if your system is medium range, and that doesn't mean a 5950U is medium range, it eats up power, i mean medium range from it's generation (so a 5700U is medium range, a 5950U is high range, as it still needs a heck of a lot of power)
Thermaltake's PSU's are usually reliable, but should not be put in a system that is OC'ed or tweaked heavily...but they are decent for stock running (to replace OEM units from HP, Gateway or eMachines...Dell is excluded, as their PSU's are from PC Power & Cooling, which is the best of the best (Dell's OEM PSU's are actually pretty nice, their just really low wattage (it's a really well made 300W PSU...so it can't do much, it's just gonna last for ever, not being able to power much)