Hi,
The timeline view introduced in Project 2010. So it's not available in 2007.
If you are looking for high level view with only few details then applying filter to show summary tasks will help you.
There is also a report by name "Top Level" tasks which displays Summary Tasks details. You can change the content (using tables and task filters), time period (or unit), and details (including notes and objects), and you can sort the data in this report.
You can access it from Report menu >> Overview reports.
Thank you,
Kiran K.