Here is a portion of my help file on OBMM.
OBMM – Oblivion Mod Manager
This is a program that makes working with multiple mods much simpler than the built in Data Files on the start menu. It has many other features such as a save game manager, a simple way to change the load order of mods, and a set of very handy utilities for working with and troubleshooting mod problems. It also has a built in Oblivion launcher that will automatically start OBSE if it is installed on your computer.
If you have more than 5 mods I recommend getting this program.
Like OBSE, it is a separate program that must be started before Oblivion. However, it can start both OBSE and Oblivion without closing its user interface. As you gain experience you will find more and more that can be done with OBMM.
Again, It is not a mod but a program and it has special installation procedures. To make it easy, it has an automatic install function. Just double click on the zip file and follow the instructions.
It is available from the authors site here:
http://timeslip.chorrol.com/OBMM as downloaded is a self extracting file. If your Oblivion is in the default location, It will unzip and install itself in the right place.
You do not have to convert your mods to OMOD format to use it, it works just fine with the default .esp mod format.
To use it, you must start it before Oblivion. It will open with a screen that shows all of the mods in your Data folder, with the active mods checked. Simple functions include enabling/disabling mods, changing load order and launching Oblivion from OBMM.
For the more advanced functions, I recommend looking at the author's site
http://timeslip.chorrol.com/