Here's a problem that's plagued my for a long time:

I have 2 xp boxes connectec through a router that's connected to the internet.
both boxes download from the internet at speeds up to 500kb/s and peaking at around 700kb/s
but when I transfer a file between the two, it takes forever.
Windows Task Manager Networking shows my network utilization at 0% - 0.02%
there has to be something I can do to change that a bit.
I'm running AVG antivirus on one box, and Norton 360 on the other.
I've tried disabling both of them, but no effect.
any suggestions would be great!