I am Computer Science student and primarily use Visual Studio C++ with Intel Compilers and Intel Development Tools. Time to time, I play Team Fortress 2. System needs to be with Intel Processor only, since tools the compilers I am using, are processor sensitive. So far, I found this: http://www.bestbuy.com/site/Dell+-+XPS+Desktop+-+12GB+M...
Decent enough system, has the CPU grunt required for what your doing. Plenty of RAM as well.
Gaming ability not so much, a GT640 isnt that powerful, but neither is TF2 intensive. Suspect as long as you don't start playing games above Counterstrike, TF2, Left 4 Dead level graphics you'l be good. If you do want to play higher tier games, youl either have to lower the settings a fair way or get a stronger card (and probably PSU to support it).
If you have a pc already why not build one yourself? The rewards of doing so and picking just what you want and need will be more then enough for your own needs and toms folks here could give you 100s of ways to do so and if you ever put something together in your life you can a pc and the feeling you have buliding your own! pc is more then enough to consider. newegg and tiger is best for parts ect first best latter second good luck.
also the info on the web google ect can reviews can point you in all the right directions to get the most for your money time and workmanship. Ive always been able to find help on the web when I am stumped no matter what the cause. Thank you toms