Newbie question - possibly OSI - don't know

Hello,

I have a server that about 50 clients access at any given time. The file
sizes are pretty large (mostly graphics and video) - from 10mb to 1 GIG.
I'm debating about going to 10 Gbe to the server but have no idea if they
would benefit. I see the network utilization averages around 50% for
gigabit on the server. I have both PCs and macs attached. I rarely see
the utilization exceed 75%. The workstations are mostly 100mbit and the
macs are mostly gigabit. I'll be upgrading the PCs to gigabit soon.

I don't know how well Windows 2003 SP2 servers handle demand in networking.
I also don't know if 10Gbit is any more or less efficient for overhead.
I'm totally new to the idea of 10gigabit and don't know squat about OSI etc
so don't feel you would be talking down to me if you need to spoon feed any
answers. I won't be doing any QOS as response should be equal for
everyone.

Thanks