It's not a supported OS. If you are using Win7 64bit Pro or higher, explore the 'XP compatibility mode' option to try and install old software like LT2005, it usually works but not a guarantee. Realize that Lt2005 updates may not install at all. If you are using Win7 32bit, it should install with no issues: perhaps you can downgrade if the above tip does not work for you. There are also some third party options outside of Microsoft and Autodesk if you want to take a chance: something called LongBow I believe, search for it on the internet.