g1smd - 11:42 am on Sep 30, 2012 (gmt 0)
Use extensionless URLs.
The rule looks good. Do you need [0-9] and [-] in addition to [a-z] here? Do ensure all URLs are lower case.
Once you have a site with a lot of rewriting you'll appreciate the simplicity that comes with the scheme "extensionless URL requests will be rewritten and URL requests with extensions are for real files such as images, CSS or JS".