Quick speed test between two servers with Iperf.

Iperf for Windows - free and portable!
http://linhost.info/2010/02/iperf-on-windows/

Server A:
iperf -s

Server B:
iperf -c x.x.x.x -P 5

[SUM]  0.0-10.0 sec  1.08 GBytes   927 Mbits/sec
(Not bad for 1gb network.)

The default test is 10 seconds, add "-t 60" for a longer test.