You'll need (mostly) the following:
1) Dual CPU Xeon 2.4ghz or better (that's 8 cores... two separate CPU's)
2) 16GB RAM
3) 64GB SSD via SCSI or SATA 3 (6GB/s)
4) 1Gbit connection.
5) Tweaking the settings to utilize all that bandwidth...
6) A mission that supports 100 players.
7) 100 players.
8) Win...