As some of you know, technology changes all the time, but not always for the better. Lately SSD (Solid State Drive) hard drives have become popular because they're extremely fast compared to a regular hard drive.
Looking at a normal SATAII hard drive, you can get a throughput of approximately 40 MB/sec if you're lucky. If you set them up in a RAID0 (striping) you can get even better performance.
In comparison an OK SSD can do 275 MB/sec and a really good one can do 575 MB/sec. Once again, if you set them up in a RAID0 you'd see a significant boost in speed.
There is however a drawback. SSD hard drives, just as USB memory keys have a limited lifespan. Then can only read and write so many times and then they fail. So far I have had 8 high quality USB keys failing on me since 2005. These are not the "Chinese" ones but really expensive ones.
Well not that much, but one thing you shouldn't do is to defragment it. Defragmentation will perform a lot of reads and writes during defragmentation, significantly shortening the life of your SSD. This may also be one of the reasons why they only come with three year warranty where good SATA hard drives come with five years.
Now we also have SATAIII and USB3, but this will not change the difference in performance on the hard drives in questions as they will just utilize the larger bandwidth to its maximum.
Speed => SSD
Durability => Normal hard drives