If you want LTC you need to put in:

  --scrypt

into the cgminer.

eg: cgminer --scrypt -o  address:port -p Username:password  blah blah

Megahash is correct for SHA256 (such as bitcoin) but for LTC you should be getting 100's KHash

Edit: I put in --algo scrypt rather than --scrypt... was thinking of minerd (it's late!)