There are two separate but important characteristics you will need to know about your mouse before you go on: what mouse interface it uses and what mouse protocol it uses. The interface is the hardware aspect of the mouse, taking into account things like which i/o ports it uses and how to check if it is installed. This is the part which the kernel is concerned with, so that it knows how to read data from the mouse. The protocol is the software aspect of the mouse. Applications need to know the protocol to interpret the raw mouse data they receive from the kernel.
The Linux kernel currently supports four different kinds of bus mouse interface : Inport (Microsoft), Logitech, PS/2 and ATI-XL. There is no sure-fire way of determining your mouse interface --- mouse developers generally do their own thing when it comes to standards. The following sections may help, otherwise you'll just have to make it up.
Inport mice includes most of the old style Microsoft mice which are shaped like a bar of dove soap. U.S. users who have purchased Gateway computers should note that the mice that come with them are not Inport mice but PS/2 mice (see below). Inport mice generally connect to an interface card which plugs into the bus on your motherboard. If the plug which connects your mouse cord to the interface card is round, has 9 pins, and a notch in one side you likely have an Inport mouse.
As far as I can tell, apart from the ATI-XL, all ATI mice (such as those on the Graphics Ultra cards) are plain Inport mice.
Logitech mice in general appear almost exactly the same as Inport mice. They too connect to an interface card via a 9 pin mini-din connector. Hopefully, it will have come in a Logitech box or have ``Logitech'' printed on the connector card so that you can tell it actually is a Logitech mouse.
There are also some truly ancient Microsoft mice (ones with ball bearings on the bottom as well as the mouse ball and a DB9 connector) which also use the Logitech protocol.
PS/2 mice aren't really bus mice at all. The PS/2 mouse interface is not on an expansion card, the mouse is connected to the PS/2 Auxiliary Device port on the keyboard controller. A PS/2 mouse port uses a 6-pin mini DIN connector, similar to the keyboard connector. Many laptops also use this kind of interface to their trackballs --- except for the connector, of course.
ATI-XL mice are a variant of Inport mice, with some slight differences. They come on the ATI-XL combined video adaptor/mouse card. Unless you know you have an ATI-XL card (and thus an ATI-XL mouse), you probably don't have one of these. It is possible for ATI-XL mice to use either the ATI-XL or Inport kernel drivers, although the ATI-XL driver should give better results.
There is also an older ATI video adaptor/mouse card called either ATI VGA1024 or ATI VGA Wonder. These cards are setup the same as the ATI-XL but use the Logitech mouse protocol. For these mice the hardware is setup the same as for the ATI-XL but you setup the software (i.e. IRQ) the same as the Logitech mice.
The PC world is full of different and conflicting mouse protocols. Fortunately, the choice for bus mice is considerable smaller than that for serial mice. Most Inport, Logitech and ATI-XL mice use the ``BusMouse'' protocol, although there are some ancient Logitech mice which use the ``MouseSystems'' protocol, and some even older Microsoft mice which use the ''Logitech'' protocol. PS/2 mice use the ``PS/2'' protocol.