X Graphic does NOT change ground scenery. It allows you to customize the LOOK of your sim by changing various 'things', such as:
Sky textures, water textures, cloud texture, airport textures, lights, sounds, and sun textures as well as having a basic weather engine (Visibility transitions).
Ultimate Terrain X, does something completely diferant. It makes the scenery more accurate to real life by adding scenery for, Highways, Roads, Streets, Shorelines, Coastlines, Rivers, Streams, Landclass, Waterclass, Railroads, Night Lighting, Object Repositioning, and some textures. None of which Active Sky X does.
Two different products doing two completely diferant things. I have both used in conjunction with eachother to deliver a fantastic looking sim.

The addons I would purchase are: Ground Environment X and Flight Environment X (Weather engine like ASX is coming out). It's a good idea to get Ultimate Terrain X or atleast some decent landclass too. I have so far been unimpressed with Active Sky X because its lack of visibility transitions, strange stutters, and pauses when it's running.
Last edited by Slotback on Fri Feb 22, 2008 12:00 am, edited 1 time in total.