Final Fantasy 1 to 6 are more for harder fans, I think. they're not the best to start with, not in year 2010 anyway. Most of my FF playing friends IRL won't even touch anything older than FF7 because of the graphics mainly. I haven't played them myself either, but I've played and enjoyed FF8 to FFXIII so I'm a bit interested in playing the old ones too now. I think you should play some of the newer ones first to see if the series appeals to you. The best place to start imo is FFX, easy and interesting story to follow and the graphics are very good too. It's a lot like FFXIII actually, not the graphics but everything else.

if you just have an xbox and a PC then I'm not sure if it's possible for you to play them legally. FF7 at least was released for PC in america, but every person in the entire world with the PC version seems to have bugged games that won't let them proceed in the game.

you could always emulate FF7, 8 or 9 if buying a PS2 or PS3 is out of the question. They're all for PSX.