Why you need it: You have an SLi rig all dressed up with nowhere to go
So, instead of knuckling under and standing in line for an Xbox 360, you bought a wicked-fast video card (or two) and blew your credit rating on a high-resolution widescreen monitor. If you are righteously nodding your head right now, these hardcore mods are for you.
The "Landscape LOD NormalMap Fix" mod combined with the "Landscape LOD Texture replacement" might sound crushingly boring, but they'll take your outdoor vistas to the max - provided that your computer's video card includes at least 256MB of RAM. Distant outdoor textures in Oblivion are actually quite compressed and blocky compared to the lush, nearby environments. These mods fix that - if your rig can handle it.
These first two mods are improvements for the lands directly around the Imperial City. If you like the results you get, download the pack for the far-reaching border regions, called "Landscape LOD Texture Replacement (Border Regions) ".
To install, unzip each file into Oblivion 's Data directory (you have a desktop shortcut to that folder by now, right?). Remember, these are extremely high-resolution textures that will crush your screen rate if you don't meet the minimum specs - but if you do, prepare for some retina-smacking views of Cyrodiil.