That's BS. It's just not marketed as running on AMD boards. You'll only need to check the RAM's settings in BIOS, which you need to do anyway. Just take a look at almost every problem asked about around here (freezing, BSODs, not posting, crashing). Nearly every one of them is caused by improper RAM settings.
Considering that once you count the combo it's $27 more ($15 normally, $12 from the combo), I think the X3 is better. There was some research done here at Tom's on how the nubmer of cores of the CPU affect gaming that found that going from 3 to 4 cores actually decreased gaming performance. Not only that, but the X3 can have a fourth core unlocked.
Since you're a gamer, I would consider this combo with the X3 and a better board first. That board will allow you to add a second GPU in Crossfire for better gaming performance.