I’m not sure if this is legal, but I think that if you own a playstation and original games it should be no problem. It’s possible to play playstation games on your computer. Even on high resolutions (up to 1600×1200).

ePSXe is a great emulator for playstation games. I’d say one of the best. It supports multiple plugins. You can choose your own video and sound plugins. Depending on your plugin you’ll have lot’s of features to choose from.
You can download ePSXe from their original website for free: www.epsxe.com
Plugins are easy to get. But finding the needed playstation BIOS binaries might be a little harder. You can find those here:
http://www.filemirrors.com/search.src?type=begins&file=scph
Different BIOS binaries to choose from. There are a couple of others, but with these you can play allmost any game.
scph1000.bin - Japanese BIOS
scph1001.bin - NTSC BIOS (Mostly US)
scph7502.bin - PAL BIOS (Mostly Europe)
I run my games in scph7502 because that’s the version of my own playstation, so all my games work fine.

PSX Final Doom in ePSXe (In window mode, 2xSal enabled)
After you downloaded and installed your BIOS, you can move on to plugins. I’d recommend the following plugins (these are for the so called “high-end” machines):
Video: Pete’s OpenGL2 Driver 2.6 (For the newer 128 mb or more cards)
Sound: Pete’s DSound Audio Driver 1.15 (Or the standard ePSXe SPU core)
CD-Rom: Pete’s CDR ASPI/IOCTL Driver 1.11
Pete’s OpenGL2 Driver is by far the best because it has so many features. One neat feature is 2xSal. It’s a technique to smooth pixels (takes up a lot of video ram though). Just look at it’s settings window:

Should you have any more questions, you can allways email me.