The default interface for AutoCAD LT 2009 looks a lot different from previous releases, with the Ribbon and the cream-colored background being the two biggest changes.
Being LT, there are of course many ways to tweak this new look to get it just the way you want it, but the product designers also thoughtfully included a couple ways to get back the "old" look if you really want it.
The first tool is the Workspace Switching icon on the right side of the status bar. Left-click, and you'll see a list of two workspaces (more if you've added your own): 2D Drafting and Annotation, and AutoCAD LT Classic. Activating the Classic workspace brings back all the familiar toolbars and menus, so it looks like AutoCAD LT 2008.
There's also a button to set the colors back. From the Display tab of the Options dialog box, click the Colors button. On the right side of that dialog is a button to Restore Classic Colors, which brings back the old black modelspace and white layouts from LT 2008.
Although I do recommend that you give the Ribbon a try, these two tips will help you stay productive as you get used to the new features.