This used to be an area of concern as only a few years ago the standards were still emerging. The hard drive should be large enough to hold all of the software that you plan to use. 5X DVD drives are supposed to be 20X speed when reading regular CD-ROMs. Older PCs with 4x or 6x drives may skip a few frames while playing some high-bandwidth video. 1x or 2x drives will likely have problems playing these modules.
Higher bandwidth is obviously desirable, if possible.
Most new machines today ship with 4 or 8 Mb. This technology is pretty much obsolete. We have found that when some SVGA cards are connected to MPEG playback boards, the combination will not support the higher resolutions required by the modules. Most of the modules with problems have had workarounds developed, however.