All video cards are SUPPOSED to keep cool with the stock cooler, but that all depends on the case, doesn't it?
I have a 5200, but my case is ****, and my video card gets HOT.
The best way to fix this is to install a fan in the center of the side that opens. It's pretty simple. Just buy a fan (if you can, get one that has a power connector like that of a hard drive or cd drive, in case your motherboard has no more fan connectors) and measure it. Cut an appropriate hole in the case, dead center (for asthetic reasons mostly) and mount the fan.
That's if you already have a fan at the back of your case, under the power supply. If you don't, put one there first. If the problem persists, put another in the side panel.
In the mean time, pop the side cover off when you're gaming. If it still gets hot, set an ordinary house fan by the computer, blowing air in. That's what I'm doing, until I get around to installing another fan.
You might also consider installing a fan in the top of your case. Side panel would work a little better though.
A method that's a little more expensive ($25) is to just get a PCI fan from Circuit City. This is just a fan that fits in the PCI clot under your video card, blowing air directly on it. This ALWAYS fixes the problem, and if you go with this, you could even do a bit of over-clocking (but I wouldn't).
Also, before you do ANY of this, find a program for your motherboard that will tell you the temperature of the inside of your case. I use Intel Active Monitor, because I have an intel board. Most programs like this will give you a CPU temp, a zone 1 temp, and a zone 2 temp. The only way to tell which components are in what zone is to play a game, and watch what temperature guage rizes the most. That's the zone your video card is in.
Most video cards work OK up to 50 degrees Celsius. If yours gets anywhere near there, you have a cooling problem.
If you can, get a temperature monitoring program that alerts you every time the temperature reaches a certain value, that way you don't keep gaming, shortening the life span of your video card.
Good luck.