RPG Maker 2000 can't load user made .dll files by default, so patches that use a .dll won't work unless the author includes an edited version of the editor designed to load it. You can download
Cherry's RPG Maker 2009 Ultimate, which -does- allow .dll loading. To quote Cherry:
QUOTE
The aim of my project is to make things easier. RPG Maker 2009 Ultimate neither changes the executable file nor replaces it. It’s compatible with all versions and this way very flexible. When started, it will load any RPG Maker 200x editor and inject itself into it. From the inside, it is able to modify the RPG Maker then.
Essentially, you run it instead of RM2K and load up your project with it, and you get a reworked interface that's smoother and much better in general. Your project isn't really affected, and can be loaded with normal RM2K at any time. Aside from .dll files, it comes with a wide range of extra features, which Cherry details on the above linked site. The project is currently frozen, but the current version is still damn good.