Gigabit speed, 100MB bottleneck?

Hello all, new to the forum here!

I have a question relating to Gigabit Ethernet, but I might as well tell my situation:


I have a small home server that I keep in my room, and have recently installed a Gigabit Ethernet card to have greater speeds. (I run a game server on it, so I need the maximum amount of bandwidth I can get.)
Getting the card to work with Server 2003 was a hassle in itself, but I do finally have Windows reporting the network is connected at 1.0 Gbps.
However, if I run a speed test on the server versus my computer, I get about 3Mbps slower on my server, both upload and download.
They are using identical CAT5e cables, and are connected to the same switch. Windows reports 1.0Gbps on both, and the switch has its Gigiabit connection light on for both cables.

I believe this may have to do with drivers and/or software, since I have well isolated any other variables. It *could* be the Gigabit card itself, but I highly doubt this; I don't think Windows would report the connection as Gigabit.

So I ask you, Tom's Hardware Forum, could you help me find a solution?

Thank you,
Infinitus