For AMD GPUs the best way to mine litecoins is CGMiner. Here is a link to a forum post with a link to the actual software:
https://bitcointalk.org/index.php?topic=28402.0Just my 0.000002 bitcoins worth.
Donations for my thoughts are always welcome:
LTC: LMfeJwB4RLMEhkCEzi7vawdCJVA5gLChYx
BTC: 162zC8bff81txGpP5U6WyHjbesDtNp1AqQ
In mine experience reaper works equally well or better...? At least for 7xxx