kk... i've been wondering about this for awhile now...who is winning in this position if both players do perfect moves?

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Nxd5 6.Nxf7 Kxf7 7.Qf3+ Ke6 8.Nc3

please show some lines as proof that white or black is better off in this position

I don't believe 6. Nc3 constitutes the Fried Liver Attack.

EDIT: Now you've correctly identified the Fried Liver.

Correction, 4.Ng5 is the two knights defense.

The Fried Liver Attack refers to a dubious variation after 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Nxd5?! 6.Nxf7!? with the knight sac.

The fried liver is meant to be e4 e5 then Bc4 not Nf3.

In my mind, black is fine in the Fried Liver.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Nxd5 6.Nxf7 Kxf7 7.Qf3+ Ke6 8.Nc3 Nb4 9.a3 Nxc2+ 10.Kd1 Nd4 and black is fine.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Nxd5 6.Nxf7 Kxf7 7.Qf3+ Ke6 8.Nc3 Nb4 9.Qe4 c6 10.a3 Na6 11.d4 Nac7 12.Bf4 Kf7 13.Bxe5 Be6 14.0-0 Bd6 unclear.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Nxd5 6.Nxf7 Kxf7 7.Qf3+ Ke6 8.Nc3 Nb4 9.a3 Nxc2+ 10.Kd1 Nxa1 11.Nxd5 c6 12.Nb6+ Kd6 13.Nxa8 Qh4 14.Qd3+ Qd4 15.Qxd4+ exd4 and black has a slight endgame advantage.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Nxd5 6.Nxf7 Kxf7 7.Qf3+ Ke6 8.Nc3 Ne7 9.0-0 c6 10.Re1 Kd6 11.d4 Kc7

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Nxd5 6.Nxf7 Kxf7 7.Qf3+ Ke6 8.Nc3 Ne7 9.d4 c6 10.Bg5 h6 11.Bxe7 Bxe7 12.0-0-0 Rf8 13.Qe4 Bg5+ 14.Kb1 Rf4 15.Qxe5+ Kf7 16.Nxd5 cxd5 17.Bxd5+ Kf8 and white's attack is neutralized.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Nxd5 6.Nxf7 Kxf7 7.Qf3+ Ke6 8.Nc3 Nb4 9.a3 Nxc2+ 10.Kd1 Nxa1 11.Nxd5 Qh4 and black is fine.

That is the bishops opening.

I believe theory says that this opening is a draw. However, care must be taken by both sides- white must keep the pressure until he manages to regain his material, and black must defend accurately. In practice, white can score better than black, but that is usually because he is much more prepared.

I could not have said it better myself.  To be honest though, this is a knightmare for black over the board.  The lolli attack is still the way to go.  6.d4!

Yes, the Lolli Attack is much stronger, and probably a win for white- why people try sacking their knight is beyond me! (O.K., I used to play the FLA, be quiet! )

Is it just me or do a lot of people REALLY like that opening on this site?

 Here are Two Main lines of the "Fried Liver Attack". It was first played by Polerio in 1590!  Computer Analysis shows both lines as virtually even, no advantage even though White has Sacrificed a Piece! That is due to the Fact that White has plenty of compensation for that Knight.
 If Black can carefully Defend... He is supposed to have the Advantage...lol Rubbish! The Databases will show you that White prevails most of the Time! It is easier to Attack than Defend. That is why people go to extremes to avoid defending this attack. I prefer to play the Ulvestad Variation with 5... b5!
 There is a Fischer Variation where White plays d4 the move before the Knight Sacrifice, it is deadly!!
 My take on this is, in the Main Lines, Black is best if he can trade down the Pieces! or Break the Pin and seek Shelter. White is Best to Complicate and Dogpile, Avoid the Exchanges!

'Fried Liver' Main Lines

Steinitz Variation
1. e4   e5
2. Nf3  Nc6
3. Bc4  Nf6
4. Ng5  d5
5. exd5 Nxd5
6. Nxf7 Kxf7
7. Qf3+ Ke6
8. Nc3  Ncb4
9. Qe4  c6
10. a3  Na6

Zukertort Variation
1. e4   e5
2. Nf3  Nc6
3. Bc4  Nf6
4. Ng5  d5
5. exd5 Nxd5
6. Nxf7 Kxf7
7. Qf3+ Ke6
8. Nc3  Nce7
9. O-O  c6
10. Re1

Fischer
6. d4

Ulvestad Variation
1. e4   e5
2. Nf3  Nc6
3. Bc4  Nf6
4. Ng5  d5
5. exd5 b5
6. Bxb5 Qxd5
7. Bxc6+ Qxc6
8. O-O  Bb7
9. f3   h6
10. Nh3 O-O-O