8 CPU's will overkill the process here, and may cuase some issues. In the other hand 4 dual core CPU's will be more relistic, and should give high performance with specs you have. DSS can use the 32G for the file I/O and the 64 for the block mode. For the ESX, we test it with 50GB and has no problem, most likely it will work as well for the 100GB.
Please keep in mind that in ver 1.30 (or later) New iSCSI, default volume creation is done in block-IO in contrast to the older versions that was file-IO. Block-IO mode is
about 30% faster then File-IO.