I'll just elaborate, ppjoy is a 16bit program its VERY old. It is not going to work on XP64 because a 64bit OS can not run a 16bit program no matter what you do.
I just redid my arcade controls, by passed the i-pac and now use my two cthulhu mc boards, these show up in windows as gamepads/joysticks so I figured I was finally golden... But alas I am still screwed! For what ever reason when I go to play 2 players and it says to press start on the 2nd player controller none of my buttons work as start, as you know it defaults to button 8, and the start button on my setup is button 10 but button 8 does not work, and I try to set it to button 10 in the controller settings from the launcher but it never sticks. Every time I go back to the settings its reverted back to default.
I found a few other people are having issues also with 3rd party gamepads. It seems to me if SF4 doesnt like your controller it wont detect one of the buttons as start.
Using the game menu and the option "select 1st player device" I can use both joysticks as the 1st player showing they both work in game, but I do not have a start button.
I have spent more money getting this game to work than I have on the game itself and its quite aggravating. I even hacked up 2 usb cables just to connect the cthulhu boards. I wont often have somebody in person to play the game with, but I want to be able to when the opportunity arises. Plus there is absolutely no excuse for the horrible job done with the control settings.
All the other forums have these capcom fan boys just saying "there is a fix try search next time" but little do they know I was one of the people writing guides on this fix over a year ago when I used it to bind the wiimote to PC, and that it wont work on 64bit OS's, Plus its not our job as customers to fix the problem its the game teams job. Heck ppjoy is not even a fix, its a work around. So we really need to make some noise and get a proper fix asap.