Enter 4SUD-A2DX-8EBU-KFFX as your profile name.

On the first level just before you go into the mueseum at the 4 way intersection if you go in the last building on the right and up the stairs I think you get a secret uzi.

First of all, I want to verify that there are absolutely NO cheats for this game. Although, I have below a collection of codes to put as your profile name, which will get you the M249 Machine Gun ( a very big gun with lots of firepower) at the start of the game.

Make this your Profile name:
FG6S - WFZG - 7MDP - PZGT

If that didnt work, try these:
HQ6G - 7P3B - C5L5 - PZGT
5SQQ - STHA - ZFFV - 7XEV
EG4P - ZGUJ - 6SQJ - 3X68

I hope these codes help you, and, if you wish to have them confirmed, check the cheats that were submitted by Team SuperCheats.