Where to start...
Wintermint, suggesting a $500+ machine when his budget is $200 is absurd.
Truth be told though, $200 cannot build anything modern. I think the cheapest new build I have that I could recommend with a clear conscience is almost $400, not including the O/S.
With a $200 budget, the obsolete-tech market is probably the best you'll do, and, with the exception of the PSU, for that money you did not do too badly. Yes, the 690 chipset is ancient technology, and the CPU has been passed by even the lowest of AMD's current line, but if you play mostly older games or are willing to turn down the settings, you'll manage until you can afford something better.
Now, if you have an additional $200 to make changes, then first we need to know where you are, or where you can shop. I will assume Newegg for these examples. The first order of business is a quality PSU. For $44, this 430W Antec Earthwatts will be hard to beat:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371034
$156 left... I really think, for balance, you'll need a stronger CPU before getting a better GPU. For $75, get the X3 720BE:
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103652 and for $20 get an inexpensive cooler such as
http://www.newegg.com/Product/Product.aspx?Item=N82E16835186035 then save the remainder toward a GPU later. Play with that system to see how much of an improvement you want before spending more money. A HD6850 should be around $150.