There is no substitute for reading the actual thread, but I will give the basic details here.
If you feel defeated by the size of it, open up notepad and paste the parts you think useful in there and save it. This way you won't have to read back through it again if you don't want to.
This thread deals with using the PS2 Guncon2 on a PC with TV-Out capabilities or an arcade monitor. PC monitor use is mostly covered by the thread SirPoonga pasted below, but is discussed in this thread as well.
For TV use, all that is required is a Guncon2 lightgun, a video card with TV-Out, Smog's Driver, and a TV. I use an ATI Radeon 9200 (PCI), with the S-video outputting to my TV and the composite outputting to the Guncon2. The card is capable of doing both simultaneously, with no special wiring or adaptors.
For arcade use, see the IntruderAlert's tutorial, linked below.
It should be known that
official Guncon2's seem to have the worst tracking problems (the infamous "Rolling X") but only on TVs. It is believed (perhaps by me only) that this issue is caused by the official Guncon2's dual functionality as both a standard and HD lightgun, if only for the fact that the generic guns that do not have this feature seem to have no problems.
The gun is compatible with MAME but cannot function well on a Black screen, so expect spotty perfomance on "joystick lightgun games", such as Revolution X and T2.
I will add more info to this post to help newcomers as it occurs, or is suggested to me.
See the links below:
[Edit]
Me:
Let me take this opportunity to remind everyone that you NEVER have to cut, splice, shave, hack, or generally mutilate ANY part of your Guncon2 or any part of it's accompanying cable to use the driver, or to do ANY part of what we're discussing.
New folks, please put your all-purpose wiring crimper/cutter/stripper away.