Newbie for Flight Sims

[dedgerly]

How do I get into flight simulations? I have an old Dell and do not know what my video card is or it's capabilities at all. I'm still running XP. The only game that I have run is the Medal of Honor role game.

Do I use a USB joystick or serial one?

Where do I get CD's with WWI flight scenarios?

What is the most fun? - realistic?

Help is appreciated in advance

Dave (old guy without tech savy)