Awesome Combat Flight Sim - Free
The graphics could be better, but they're really not bad. The controls are easy to learn, and if you're using a keyboard, the arrow keys are slow at first, and then speed up majorly, but you get used to that after about 10 minutes, and I'm having no problem beating 5 migs with 1 F-14 - and the difficulty is actually quite realistic. Of course my wingman's an idiot and gets shot down every time, but I highly recommend the game. The download's quick, and if you turn too sharp - you start to black out - the screen contracts.