Right now, RMXP probably isn't the greatest thing to use unless you want to learn its scripting language (which according to some RPG Maker sites, is one of the worst ones they could use.) If you want to do anything the maker doesn't let you do (like 2k3's side-view Active Time Battles,) you have to program it yourself. XP also puts limitations on originality since it's generally harder to create appropriate original characters and creatures (or ripped stuff) that looks proper in XP's color depth. So unless you really know what you're doing, or have the patience to create a bunch of stuff to make it do what you want, I'd avoid RMXP right now.