Though hardly specific to Project64, understanding and having good ROMs is so important to using Project64 successfully that I'm going to cover it briefly here.

First you need to download the following from Emutalk N64 Downloads:

1. The latest version of "GoodN64" by Cowering
2. "GoodWindows" by Master of Puppets Or "GoodGUIv1.4" by polarz
3. a file called "bin.zip" containing "zlib.dll", and some other files you might need.

If your ROMs are compressed, you need to download whatever utility is needed to decompress them - for example, if they end .zip, download and install WinZip, if they end .rar, download and install WinRAR, etc. etc.

Have your unverified and decompressed ROM files available somewhere on your hard drive, e.g. "C:\Temp"

Unzip all the utilities listed above to one folder on your hard drive e.g. "C:\Program Files\GoodTools\" (zlib.dll should end up in a "\bin" subfolder of this folder). Browse to the folder and run GoodWindows.exe.

1. Select mode "Good Tool"
2. Select "Nintendo 64" as system. You will be prompted to browse to GoodN64.exe. Do so.
3. Set "Directory to work on" to the folder containing your unverified ROMs ("C:\Temp" if you are following my instructions exactly)
4. Keeps "Options" set to "rename"
5. Press the "Execute" button and wait until the program is finished. This may take some time.

Close GoodWindows and browse to you ROM folder ("C:\Temp" if you are following these instructions exactly) , and you will find GoodWindows has created some subfolders and text files. All known ROMs have been moved to a subfolder "N64ren". Any ROMs that are not moved and not renamed are not known by GoodN64, it is safe to assume they are bad - probably best to delete them.

So how do you know which ROMs are good? It's very simple, a good ROM will now be in the "N64ren" subfolder and have "[!]" in its name. If it does not have a "[!]" in the name then there is something wrong - the full key is included in GoodWindows, under Legend > Good Tools.

Only "[!]" ROMs are supported by Project64. If your ROM is not good, find another. Usually ROMs that are not good don't even start but sometimes they fail midway during a game - you do not want this!