Any of the latest offering are going to fit the bill. They are leaps and bounds better than your current system. But, since you seem to be budgeted, be sure you have room to grow on. That means that any additional needs like more ram and/or drives, or pgms. demands, etc. will be meant by the PSU. Those systems sold by OEM's tend to fit only what was sold as, they fail under added stress to the PSU. But, often work quite well with some TLC during use as is. Continue to check several vendors as well as hi-end systems just to see what differences are present if anything else. Remember, cheap is cheap.
my barton 3000+ with 1gb ram will not play mp4 or mkv videos without lag getting out of sync. (my ipad2 with play them seemlessly!)