CrystalDiskMark is a synthetic test that evaluates both sequential as well as random small and large file transfers. It does a nice job of providing a quick look at best and worst case scenarios with regard to hard drive performance, best case being large sequential transfers and worse case being small, random 4K transfers.
Seagate Barracuda XT 6G
Seagate Barracuda XT 3G
Western Digital RE4
Seagate Barracuda 7200.11
The Barracuda XT offers measurably better performance than the 7200.11 edition drive, but the WD RE4 takes the top spot here. The WD RE4 is a bit slower then the XT in the sequential write test, but in every other the WD drive leads.