Not sure off the top of my head what DA recommended but I can tell you what I use to run dedicated.

It's P3 1 gig w/ 512 meg memory and with 15 ppl in at the same time the processor usage is almost at 100% (actually going from 70% to 90% or so). Bandwidth usage averages at 15Kbytes upstream with peaks to 20 or 25 (but Im using remote desktop so with changes on screen while viewing server console there is data included in those numbers as well for desktop updates). Currently Id say the machine power plays almost greater role in overal performance than net badwidth (which is rediculously low if you ask me).

Oh btw. the mem usage of FLSERVER process is about 130 megs not more with being at 30 megs on server startup.

So far its hard to make conclusions as I would have to have more simultaneous ppl online to monitor and try figure out where the limit is.