>I am trying to network a shop that is going to be right at 100m away from the router. If the router is 10/100 and the card at the other end is a 10/100 card with the components "downshift" to the 10 mode, or is the 100m hard no matter if I don't mind operating slower?
I'm not sure, but you may able to configure the cards/driver to operate only at 10 MHz, many allow it. The reason I am not sure is the 100 Meter limit on 100BASE-TX is imposed by timing limitations imposed by the time allowed to send packets down the pipe and the return of any collision signal (i.e., a 2-way trip), not necessarily by cable quality, etc. BTW, the 100 Meters is from absolute end point to absolute end point (in a LAN it would determine the maximum distance between the PCs that are furthest apart).
>Also if I put a powered hub in will that give me another 100m of segment length, or is there some type of repeater ability that I need to be looking for?
An Ethernet segment is an Ethernet network or a part of a larger network where devices such as PCs share the communications media in what known as a collision domain. Two computers networked together with a crossover cable (http://duxcw.com/digest/Howto/network/cable/cable1.htm ) comprise a simple Ethernet segment. As the two PCs do not have to listen for collisions that could be caused if additional PCs/devices were on the same segment, trying to transmit packets at the same time, both computers can send and receive data simultaneously using a full-duplex mode. More than two computers networked together with straight-thru cables and an Ethernet hub also form an Ethernet segment. They share the Ethernet segment using the Ethernet Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol. They operate at half duplex because they must listen for collisions with their receivers. An Ethernet switch forms separate, temporary Ethernet segments between it and the communicating devices, eliminates packet collisions, the need to listen for collisions, and allows full duplex operation between the devices connected to the switch. See http://duxcw.com/faq/network/hubsw.htm and http://duxcw.com/faq/ics/diffrout.htm for more info. The maximum distance between the end points (e.g., two PCs) of a 100BASE-TX segment is 100 Meters. This distance includes all cable, including jumpers and cable slack, between the end points. Ethernet hubs are repeaters, which come in two flavors: Class I and Class II. In a 100BASE-TX Ethernet, a simple Class I repeater supports only the devices connected to it and cannot be cascaded; i.e., to form more than one segment. In a 100BASE-TX Ethernet, a Class II repeater will support one hop (a hub to hub connection) to another Class II hub to form a network with two (overlapping) segments. Two cascaded hubs (or hub and switch) have a maximum network diameter of about 205 Meters. A Class II hub or switch (cost nearly the same) should work. The maximum distance between hub/switches is 100 meters. A switch by itself will stretch 200 meters (each PC is on its own segment) between end points. So, perhaps, another alternative is to move the router/switch so it is closer to the remote PC. http://duxcw.com/dcforum/jar.htm.