I suppose it depends how long the 10GB files run for - it sounds like
an awfully long video. Typically that might amount to around a days
worth of video per file at 1MBps, or 2.5 hours of WMV-HD at the very
top end (1080p) of the encoding spectrum.

So, the network requirements are basic maths here - 10mbps * 20 users
= 200mbps (so you'd need a gigabit network + cards).

Data transfer would need to be at least that, about 25MB per sec from
your hard disks - so at least 7200 and possibly 10000rpm hard drives
would be useful. You can expect "fast start / fast cache" features to
double that data rate at the initial burst of stream startup.

The CPU shouldn't normally be a limiting factor, all it has to do is
move bits from the hard drives to the network interface.

There's a word doc with useful information about sizing requirements
http://download.microsoft.com/download/8/f/4/8f47ea6a-254a-421b-9542-c3e5965c8be
7/optimize_web.doc

I guess the likelihood is with many 10GB files, you'll be using a SAN
or NAS to hold that content. There's also an article on that here :
http://www.microsoft.com/windows/windowsmedia/howto/articles/SourcingRemoteConte
nt.aspx

HTH
Cheers - Neil
------------------------------------------------
Digital Media MVP : 2004-2007
http://mvp.support.microsoft.com/mvpfaqs