Just as a contribution. the LCD screens draw hardly any current, thats why they are used in laptops. Cold cothodes arn't too bad on current draw, and the LCD circuity dosn't require a whole lot of juice (compaired to a computer processor)
Thumbscanner, I'm sure it draws next to nothing and could run off the current a 9V batter supplys.
PS2, They don't draw a lot, but I'd guess somewhere around 200-300W Computer, well, you should know how much wattage it draws prolly significantly less than 500. The subwoofer, you have a 3 farad buffer in-line with it's power source, and even if it is a 3,000 W amp (which it looks like it is not) it's not a whole lot for a 100+ amp alternator unless your bumping sine waves constantly...
Yes, there's either a big electrical fault in your system, it's not getting cooled at all, or you just got a bad alternator. I'd definately get a better\new battery. Get the biggest optima you can fit in there. Yellow top is probably what you'd want, nice compromise between electrical release characteristics and amp hours.
I'd get someone to rebuild your alternator and say what they though went wrong as well, then you could possibly tell if it was just a failure or electrical overheat.
Yes, It is strange to blow and alternator, and then blow the 2nd one you put in fairly soon after you replaced it..... something is probably wrong.