Welcome to the Mod/Forums, Vip3r. 
The new BS:G Vipers and even the Babylon 5 Starfuries would cause serious problems if they were allowed to use their own, 'real' physics. They do move more realistically in a combination of zeroG within a vacuum. That said, zero-G alone is in effect in FS. Trust me, it was kind of odd in GC when you constantly had to give thrust to keep the nose of your fighter up. 
Star Wars, however, has never had "real physics". Watching the films will make that obvious: every ship seems to be flying in an atmosphere (if not on wires).
Just a different fictional universe.
If you need some kind of 'real' explanation... um... Well, it was a long time ago in a galaxy far, far away. Maybe their galaxy had some atmosphere. Or... those midichlorians were everywhere, back then. 
_________________________________________________
a.k.a.: Grandma Tarkin // hQ.Terrorek
Today's spelling/grammar tip: There = a (sometimes conceptual) place. "There is my car." or "There is such a thing as magic." // Their = posessive. "Their meat is full of worms." // They're = contraction of <they are>. "They're crazy!" // "They're trying to put their shoes up there."