*fast* Nics, Lots ¡Æo ram and multiple processors. Disk space isn¡Çt a huge consideration, but ensure you have enough to hold twice the index  file sizes.

Another from memory answer but I believe that the Index's are
between 15% and 30% the size of the original files. To that end you
might not need lots of space on Hard Drives but should budget in the
size issues and make sure yu have enough scope for growth..