Thanks for all the input so far.
Maybe I'll really have to look into this...

I would start with HG/SS myself as well. If you enjoy them (which I'm sure you will) I would move on to Black/White and then maybe Platinum.

Playing one pokemon game feels so awesome its that playing more then that isn't as fun if you play back to back sine its new games with more content(Which is a good thing but not something you would play back to back) So if your going to buy one start with black or white since they are better then the previous ones and if you like enough buy the DS ones and if you still like them go even earlier

Since Gold and Silver are the best ones, and Heart Gold/Soul Silver are better, upgraded versions of these games - I recommend starting with HG/SS :) B/W are good too, though :p

(heart) gold and (soul) silver are my favourite Pokemon games.

They are so similar that you probably want to play the best one first time round, so go with the 2nd gen.

The original Red/Blue/Yellow of course, start from the beginning.

I'd start with: (In this order)
pokemon firered/leaf green,
pokemon heartgold or soulsilver
pokemon emerald
pokemon platnium
and pokemon black and white

just play all of them from first to newext gen damn son you missed out big time get on that asap every game is awesome