"Besides the recording technology, drive rotation speed is the most important factor for a drive's throughput. Most people associate fast rotation speed with high data transfer rates, because this is the most obvious advantage of fast spindle speeds. Whether you boot Windows or copy files that are hundreds of megabytes or even gigabytes in size, quick transfer rates shorten the time it takes for completion of these tasks. Combining high rotation speeds with top-notch recording technologies such as PMR (perpendicular magnetic recording) has repeatedly managed to establish new speed records."
Source.
In addition to the base system requirements of Fraps 2, hard drive speed is important when capturing video. We recommend: 7200 rpm hard drive for full-size capture at 640x480 and 800x600.
10000 rpm hard drive for full-size capture at 1024x768.