Right now the cutting edge of Nvidia scrypt mining is cbuchner1's cudaminer:
https://bitcointalk.org/index.php?topic=167229.0Still not as good as an AMD based card, but substantially better than any other miner for scrypt on nvidia.
It auto tunes its own parameters, so its actually the easiest to use scrypt miner out there. Just feed it a non stratum pool, a username, and a password. (or use a stratum proxy).