Geez liquid, save some of the questions for someone else. j/k
Hey fox5, in addition to liquid's suggestions you can also download ePSXecutor1.04 which has the mdec on/off options. It also allows you to make custom configs for individual games. Very handy if you find yourself reconfiguring all the time.
Hmm..well except for VR missions, I can't really think of any times I would need to reconfigure....except maybe on some games that don't work properly with Lewpy's glide driver thing(like Final Fantasy V for example, which doesn't allow you to see the item or skill menus if you go into the menus, however in battle everything is fine) and instead I could use Pete's OpenGl, which works better but doesn't run even half as fast.