Yes. That upgrade will make a considerable difference, esp. if you run things that can benefit from the extra cores (ie. encoding,etc). Games that are not CPU bound will not benefit. However, games that are CPU bound (ie GTAIV, FSX,etc) will benefit from the X4.
In any case, this is a pretty noticeable upgrade. Btw, in your link you are going X2 vs Athlon II X2 which only makes a little difference.
This should be your comparison: http://www.anandtech.com/bench/Product/27?vs=122