Check this out!
https://bitcointalk.org/index.php?topic=167229.0MAKE SURE you put -C 0 in your launch options, that option is broken currently. Hopefully he will put out an update soon that fixes it because it improves performance a ton
Also, READ THROUGH THE WHOLE README, you will probably increase your performance. If you need a little guide I'll write one but you should be able to figure it out.
According to the README.txt:
this is a CUDA accelerated mining application for litecoin only.
I'm still boggled by why there is so much non-Bitcoin alt-currency activity on the
Bitcoin Forum at
bitcointalk.org... but... whatever. People should specify if they're talking about LTC instead of BTC... but based on face that OP said he "can't get past 50Mh/s" on a nVidia card, it is logical to assume he's mining BTC.