Okay, lets put 3 cases. Case 1 gaming, Case 2 general computing, Case 3 watching HD content.
Before we even begin, check your motherboard. Does it support PCIe 2.0, 2.1? I have heard that PCIe 2.1 cards would not work on older PCIe 1.0 slots, just not compatible. If your mobo has the newer PCIe lanes, read on.
Case 1: go with XFX. Its just a couple more $3, but you get a much faster processor, which is directx 10 capable that would be pretty good on your system as I am presuming its a consumer based system. You get twice as many stream processors, so better rendering, and 1 GB of RAM on it, providing better gaming experience at medium to high reso at low-medium game settings
Case 2: You will see a speed boost in web browsing and watching Youtube, vids would play without lag in full 1080p full screen on youtube, but your Internet connection may slow it down in terms of buffering. System would work faster when watching video, opening multiple windows explorer windows, viewing pictures, working in photo editing software, etc. In this case, both would work, but I recommend the XFX
Case 3: More raw performance in a card=better HD video playback. It will offload your CPU usage when decoding HD videos. Also, the faster the processor clock, the better, but in this case, you will not see much of a difference. I would go with XFX again.
Conclusion, give XFX a shot. Their customer care is probably one of the finest, card has good specs and price ratio, and comes with limited lifetime warranty. Good luck.