Welcome to PC! You only just got a DS? Aww. DS' have been around for a while, why only now? XD I've never played Platinum, but most people say it's pretty good, so yeah. I do know that HeartGold is a good fourth generation game, but it's mainly aimed at those who have played G/S/C (though to be honest it suits everyone). Either way, HG/SS is enjoyable for most anyways.
PC does have some interesting ideas, some very interesting ones. XD If you need help or something around here, feel free to send me a Private or Visitor Message~