You can order a free AutoCAD® 2005 Trial CD-ROM or a run the fully operational online AutoCAD® 2005 streaming trial.
AutoCAD® 2005 30-Day Trial CD
(This offer is valid only in the United States and Canada. For countries outside the United States and Canada, contact your local Autodesk Authorized Reseller)
Link to Order Form
AutoCAD® 2005 Streaming Trial
(Stream a full version of AutoCAD® to your desktop for 30 consecutive days at no cost. Create, view, save, and plot your own files and fully experience exactly how AutoCAD software operates in your work environment.)
Link to Streaming Trial
Make sure to have a look at the documentation to see what some of the new features are.
Link to Features Documents
Comparing AutoCAD 2005 with Previous Releases PDF White Paper