ePSXe is the most popular PSX emulator for the PC. It runs almost any ps1 games, either thru the cd rom of your PC or save it on your your hard disk (should be ISO extension, or convert your ps1 cd's to ISO). Although it runs almost any ps1 games, there's still some lock-ups and bugs which you can just search the web for a fix.
I uploaded the emulator thru mediafire (1.7.0 is the latest version), just extract it using winrar or 7-zip then run ePSXe file, insert your ps1 cd, click file, then select run CD ROM. This is the most complete and updated version of ePSXe without having to download its BIOS. Everything under one file to suit your gaming needs.
To change the control pad:
Here is the link and the password for the file: (password in red color)
password is: piratedcd.blogspot.com