Mod Name: Saddle Bags
Why you need it: It's about time your horse started pulling its weight
There are a variety of mods available that clearly change the nature of the gameplay, but the Saddle Bag upgrade simply enables your mount to do what he was born to do: carry your stuff. This mod also works just fine with the official (sniff) horse barding upgrade (horse armor), and transfers automatically when you buy a new steed. It even includes a mini-quest that, if completed, will improve the performance of your horse. Yee-haw!
Character horses like Shadowmere (the badass mount you'll receive in the Dark Brotherhood quest line) cannot be killed. So, if like us you had the bad habit of knocking him out just to loot his corpse - or plant your dungeon-sweeping plunder onto his lifeless body - install this mod today. (Before we call the Humane Society of Chestnut Handy Stables on you).
Installation is easy. After downloading the file, unzip it onto your desktop and you'll see the automatic installer. Double-click that and choose the "horse armor/no horse armor" option. After checking the box in the Data Files menu of the Oblivion launcher, you are all set. Saddle up.