The Kingston HyperX is a bit of an oddball in that it runs an unusual clock speed of 1,625MHz.
You'll need a motherboard with some decent conﬁguration abilities to run the HyperX at anything other than a clock speed of 1,600MHz, which means you'll be losing a small part of the RAM's performance.
However, if there's one thing this test has deﬁnitively proved, it's that 4GB is better than 2GB and the HyperX outperformed both the faster 2GB kits and some 4GB kit.
In fact, the Kingston HyperX has a full 3Gb/s extra throughput compared to the Crucial Ballistix, and produced one of the best 3D mark scores, although the difference is pretty marginal.
If you have the money to spend and are running a copy Vista 64-bit, you won't be disappointed with the performance.