Im running Windows 7 and my current hard drive is - Samsung TSST TS-H653A (300 gig) i have ran out of room so just purchased a Western Digital Caviar Black 1TB SATAII 32MB Cache and the link to this is:
Probably not a lot of difference, although I could not find the Samsung's spec to verify. A lot of people like haing their OS on a separate drive from all their data so that, if a falure or corruption happens, they can re-install or even replace the OS and still have all the data safe on another drive. To do this, read up on how to change the location of all your default data file folders, like My Computer, My Pictures, etc. In your application software like Office, check how to set the default file locations.
One small tweak you can do involves the Swap File. That is the place where Windows temporarily shoves data from your RAM when it gets full, and then retrieves it when it is needed again. If it is on your C: drive, there are times when this swapping action is competing with other data access tasks and it slows you down just a little. But within windows you can change where that file is located, so you can tell it to put it on the new drive to avoid those occasional waits for access.