I want to tell you how you can have more than one mod installed at the same time without any of them interfering with each other. It's quite simple really. The magic word is "set APPDATA=%cd%". Oh, you want to know more than that?
Ok, I've made some screenshots that will explain how to do it.
|Vanilla, Mo'Creatures, More creeps and weirdos and Water shader. Each in their own folder.|
javaw -Xms512M -Xmx512M -cp Minecraft.exe net.minecraft.LauncherFrame
Now click on "start minecraft.bat" and it will open a CMD window and then start the minecraft launcher. Log in and let the game download all the files. Congratulations, you now have a clean standalone version of Minecraft. You can now make a copy of the Minecraft Vanilla folder, paste it on desktop again, rename and install what ever mod you want into that new folder. You can do this with as many mods as you like. Each mod lives only in the folder is was installed to and do not interfere with the other installs. You can even have old versions of Minecraft installed this way with old mods that have not been updated to latest Minecraft.
The -Xms and -Xmx arguments are the java heap size. By default Minecraft will allocate 1 GB of memory which is overkill in most cases. Just press F3 ingame and watch on the right, how much heap size is being used. 512 MB should be more than enough for most cases. You can increase the numbers if you have a very demanding mod and/or a HD texture pack installed. Just watch the memory being used to see how much you need to allocate for Minecraft.
Questions and comments are welcome..