Running 2007 on Nforce 2,

I've got a remote HD media streamer/NAS (Popcorn Hour)
and when I'm copying ISOs from
my PC(nfs client) to the NAS(nfs server) the CPU hits the roof.

Is this the nfs-client or is it the ethernet driver?
IS there a simple way to tell. I guess I should try ftp first ?

If that doesn't work I may have to dig a realtek nic out of the attic!

Well it started off as a question, but as I types I realised ftp client
in user space should help me pinpoint the problem. and now I've typed
too much to just delete it!