I would like the NavigationBar to behave the same but would like to change the appearance of it. I’ve found so many ways of doing this online but I’m not sure which one is the best result for iOS 5.0. The navigation bar will look like this:

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Since you are targeting iOS 5 i would definitely go for customizing UINavigationBar using the Appearance proxy. Then you can easily set your own images and they will apply to all navigation bars in your application without subclassing.
You can also customize the buttons in the navigation bar by customizing UIBarButtonItem. There are method like
backButtonBackgroundImageForState:barMetrics:for the back button andbackgroundImageForState:barMetrics:for the other buttons.