Online play, savestates, easily swapping memory cards, unlimited memory cards, graphics enhancements, novelty value, turning off the framelimiter and skipping through scenes quickly, being able to play imports without modding, etc. The list goes on and on .
I personally have two benefits. One: my TV can remain free for other family members. Two: I think pete's plugins makes games look much more beautiful & neat. Besides that its really fun to play something on a pc that you are not supposed to play.
1. Keep requests and such in one thread. Asking about netplay in here and your online play thread is confusing for other members and is hard to keep track of.
2. Use the edit button instead of triple posting.