1Gb LAN, 100 Mb WAN - why can't get 1Gb speeds?

I have a brand new DELL Precision T3400 workstation (2.6 GHz Duo, 3 Gigs of RAM, 7200 SATA 3.0Gb/s HD) which has a Broadcomm 57xx Gigabit networking controller. My university's WAN is 100 MBits. I often need to transfer big files between comps for data analysis (1..10 Gigs). So I got myself a Dlink Gamer Lounge router and set up a local network. Well, I am only getting standard slow 100 Mbit speeds (~15 megabytes per second). I test this by cutting and pasting a ~400 MByte file from share to share. It takes ~30 seconds to transfer the file over the router. Roughly the same rate as over a USB 2.0 hub.

The Windows built-in performance monitor shows a 10% saturation of the Gigabit speed - consistent with my observations.

Does the fact that the WAN is 100 MB limit the transfer speeds? Is there a way to saturate the transfer speed?

I agree ! your router as well should be supporting gigabit(10/100/1000) as well.The WAN side would'nt be an issue in view that you transfer files locally.