Network card, PCI, 10/100 speed.

What this can be used for:
connecting to network = for file transfers, games etc between computers with network cards
broadband internet (Jetstream etc) = many broadband modems / routers can be connected to by network cable
connecting to Xbox = Xbox must have been modified, eg: have modchip installed. Can transfer files to/from a Xbox, use for Xbox internet tunneling (playing games online without Xbox Live), etc

Will fit in any computer that has a PCI socket, this is common in all computers made for many years.

You will of course need to add network cables to connect from this to any other device.

Compatibility:
Windows 95, 98, ME, 2000, XP, Vista, Windows 7, WinServer 2003, WinServer 2008
WinCE 2.x(for x86), WinCE 3(for x86), WinCE.NET, Embedded NT4.0
Linux, FreeBSD
Novell Netware
Unix
MacOS
BeOS 4.x, Beos 5.0, JavaOS , pSOS, QNX
OS/2, Microsoft LAN Manager
Windows NT 3.51, Windows NT 4
DOS
Windows 3.11(maybe) = I can't find drivers specifically for Windows 3.11, but as there is DOS drivers it seems fairly likely it would work.

NOTE: Some drivers aren't on the disk, but can be downloaded at link below(later Windows versions may also have suitable builtin drivers):
http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=6&PFid=6&Level=5&Conn=4&DownTypeID=3&GetDown=false

Comes with drivers on 3.5" floppy disk (drivers can be emailed if required)