Maybe this will help someone. This is a step-by-step guide (intended for real beginners and command line haters) to mine Litecoin on nvidia, with Windows.

I mine using cudaminer on coinotron.com, and all my sample lines will be for this combination.

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1. Get all the executables, extract them wherever you like:
Cudaminer thread: https://bitcointalk.org/index.php?topic=167229.0

getwork>Stratum proxy: https://github.com/CryptoManiac/stratum-mining-proxy
This is required for pools that are Stratum-only, like coinotron.com. Beware that there is a very similar executable for bitcoin which does not work, since litecoin need scrypt support.. or something like that

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2. Register on coinotron.com, create a worker in their system, set it to LTC and RBPPS (Round based pay per share). Note the workers name and its password (Which I will call workname and workpass below)

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3. Create .bat file to launch proxy.

Proxy: Open notepad, type mining_proxy -pa scrypt -o coinotron.com -p 3334, save file as proxy.bat in the same place where mining_proxy.exe is.

Launch proxy.bat and leave it running, allow it through the firewall if it asks.

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4. Autotune cuda miner to your videocard:

Create a .bat file with notepad with this:

cudaminer --device 0 -t 1 -o localhost:8332 -O workname:workpass

Save as autotune.bat
Free your computer of all GPU usage (media players, games, etc.) You can even reboot to be on the safe side. If you plan to overclock - now is the time, as autotune may find different numbers for that.
Launch autotune.bat and let it do its magic.
After a minute or a few you will see a line xxxx khash/s with configuration ***x*. This is the number you are interested in. Remember it.

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5. Create a .bat file with notepad to start your worker with this line:

cudaminer --no-autotune -l ***x* --device 0 -t 1 -o localhost:8332 -O workname:workpass Replace ***x* with the number you got from autotune.

Save as whatever you like, this will be your miner starter file.

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Notes: If you have multiple video cards, you select which one to use with the --device 0 command (change the number to whichever card you want to use). You should autotune each one separately.
I use separate miners because I keep one 24/7, and use the other (on my main card) only when it does not interfere with my graphics.

If you have SLI - disable it. Two separate cards do more work than SLI config.. I don't think that miners are even capable of using SLI's capabilites..

Save .bat files in the same folder as the executable it launches.

Launch cudaminer with -h command to see what else you can do there.

If you are getting errors in the miner that say something about JSON and 15 second retry, most likely proxy is not working properly or you have messed up worker name and password.

If you overclock and nvidia driver crashes during mining, most likely OC settings have been reset and need to be reapplied (at least this is true with MSI afterburner).

If you find this useful, feel free to put a donation to the wallets in my signature

If you see a way to improve this guide - tell me

I will watch this thread and try to answer your questions.