Brother International does not support their line of multifunction printers in Windows Server 2003. Well, they do support the print functions, but if you want to use the Fax or Scanner functions you are SOL. I would guess it has something to do with them offering a nice network fax and scanner driver as an optional but expensive accessory, but I digress. I wanted to share the Fax Machine off our Brother MFC-8440 printer with the rest of our IT Department, but being that it wouldn't work with 2k3, and XP doesn't allow you to share faxes.
So what I did was methodically combine the Windows XP Drivers with the Windows Server 2003 Drivers so that I was using the most up to date file versions, then edited the associated INF files so that it would install. After some tweaking and some wall to head interaction, it's working great and we can fax from any of the computers in our office using the wonderful Microsoft Fax Services. The driver files are available here: http://www.alwaysnetwork.com/wss/brother-mfc-8440.zip.
While editing the drivers, I think I have made the correct changes so that it will work with Vista, but I am unable to check as I don't have any Vista boxes laying around. Also be aware that these drivers, while tested on my systems here, come with no guarantee that they won't hose up your system and come with no warranty what so ever.