PCSXR is my personal favorite emulator for playing PSX games. There are other choices but I have found PCSXR to work very well, be easy to set up and to me compatible with all of the games that I have tried.
You will need the PCXSR program, a bios from your PSX system, the nuvee light gun plugin and a backup copy of the game you want ot play.
This wikipedia page gives you a good overview:
It is pretty old so don’t expect to find a lot of current development or chat about it but it does just tends to work, it runs all of the games and lets you improve their graphics to a degree. It will also look much better on modern TVs than the original console.
Here is a decent tutorial on getting started:
This video gives you an idea of the sort of graphics improvements that you can achieve:
I haven’t been able to find many tutorials on setting up Nuvee with PCSXR so I will have to put one together soon. In the meantime, You can follow the guides for PCSX2 which uses the same plugin and the same process.
Very briefly, you need to download and extract the nuvee plugin from here: http://pcsx2.net/download/send/41-win-plugins/12-nuvee.html
Then you should copy the dll file into the pcsxr plugin folder. Once that is done, select it as a controller plugin in the plugins menu.
Its pretty much set up by default. you do need to go in and select the game that you are going to playing the configuration tab but don’t change much else.
Follow the instructions in the PCSX2 guides to get a better understanding.