There are 4 good tests to see if cards are fake.

1) If the packs do not come in a foil/mylar type packaging , they are fake.

2) If the cards, when held to the light, are excessively transparent, especially compared to known real cards, then they are probably fake.

3)  You can bend a normal (English) card a slight bit without an creasing.  If a 45 degree bend causes a crease in the card, then it's probably fake.

4) Fakes are almost always grainy and blurry.  Inspect it very closely for clarity in the pcitures.

In addition, if you see non-holo versions of cards known only to be holo, then you probably have a fake on your hands.

If you do notice fakes and can trace their origin, be sure to contact Wizards on this - they would be very happy to know about it!

Scott