Alpha numeric characters are numbers and letters. The program is telling you to only use letters numbers in doing whatever it is you are trying to do, as opposed to using symbols such as ";[]\,./?!@#$%^&*()-" etc.
Depends, if a game would not run on a xp there could be three problemsComputer lacks system req.Game was built for vistathe game is older than the xp operating systemIf you want to run an xp game on a vista it should work just fine. in some cases it will not work. but its a 98% shot it will.
If you want to make your computer run faster delete any programs YOU added to your computer but NEVER EVER DELETE WINDOWS PROGRAMS OR PROGRAMS THAT YOUR COMPUTER COMES WITH! or you may destroy or also know as crash your computer.