##Upgrade Roadmap for CE 1.9.0.1 from 1.7

1. Take a backup of current database and current 1.7 code. place maintenance.flag file inside 1.7 code folder to put website offline.
2. Download latest magento from the http://www.magentocommerce.com/download
3. Remove all folders and files from your 1.7 code except `maintenance.flag` (but you should have backup somewhere) and place all folders and files from the 1.9.
4. Now from your 1.7 merge your following custom folders into the 1.9
    - Community `app/code/community`
    - Local `app/code/local`
    - Media 
    - your theme or package (`app/design/frontend/default/<your theme>` or `app/design/frontend/<your package>`)
    - custom folders from Skin (both for adminhtml and frontend).
    - copy your custom xml files from `app/etc/modules/` to current `app/etc/modules/`
    - any custom admin theme folder from `adminhtml/default/yourtheme`.
    - copy your custom folders from `adminhtml/default/default/` (1.7) to adminhtml/default/default/ (1.9).
    - custom js files if any from `app/js/`.
5. Now go to `app/etc/local.xml`.Edit database details their.put your database username and password and database name.
6. Remove `maintenance.flag` file and check the site in the browser. it is done.