It's in beta, but if you don't mind taking your chances, or have an extra computer, it's now easy to upgrade to Windows 10, either from Windows 7 or Windows 8. It's done with Windows update.
- Click start upgrade now
- Run the upgrade tool
- Your computer will be rebooted
- Windows update will show an option for Windows 10
- Follow instructions from Windows update
Maybe my laptop is old and slow, but just a heads up that the entire process took all day.