We have an NT Intel "building block" server that consists of:

2 x 400 MHz CPUs
512 MB Memory
2 x 3 disks (9.1GB) mirrored for Op Sys and database
24 disks (9.1GB) for the disk cache.
Attached to a DLT Tape library - 4 drives and 84 slots.

We haven't fully loaded it yet to need a second building block - but it
seems to be the disk for the database that is going to become the bottle
neck first.

Cheers, Chris