Originally Posted by sbm12

Both of those will suffer a similar performance hit when running on a full HD. The fact is that data seek times - and consequently performance - improve when the drive is not so full. This is true across just about every file system out there and not specific to Windows, NTFS or any other MS-specific bit.

Back in the day memory or processor power were the limiting factors in performance because they were the throughput bottlenecks in the computer. Today it is the hard drive. The performance diffrence running the EXACT same applications/OS on the EXACT same hardware, changing only the HD performance metrics is absolutely real and significant. A 4200 RPM HD versus a 7200 RPM drive yields a completely different user experience, much more so than upgrading from 2GB RAM to 4GB or from a Celeron to a Core 2 Duo processor.