Hardware for server running CentOS 5.1 serving +50 clients

Hi,

There is about 50 clients in my network, So I can share my opinions:

Server:
Server speed and network speed if important only when syncing. When all clients finish downloading media, there is almost no transfer (only stats and network state signals).
You can simple compare it to downloading your flv's from http server using 50 normal ie/firefox browsers, and playing them locally after download. There is no online streaming from server or something like that.
Xibo server since 1.0.4 acts (and generates system load) like ordinary http server that sharing it's files (with small exception when checksuming uploaded files once) so You don't need any extraodrinary hardware.
Raid? stripe is probably not nessessary. mirror is fine when you don't want to loose whole server one day ;)

Clients:
I think there will be no difference between nvidia in other vendors when playing flash movies. One difference that i've found: Nvidia ION chipset and geforces >=8400gs contains CUDA technology, that can be used to speedup some operations, but you need to have cuda support in system for particular usage. For example, we're using cuda aware coreavc codec do decode full hd mpegs with almost 0% cpu usage. But i've never heared about speeding up flashes with cuda.