In your situation, I too think Selenium is the best way to go. Watir is a good tool too, but there is no built-in record/playback tool. There are references to a add-on, but could never find it.
If your team is inexperienced, they can start learning by record/playback within Selenium and then editing withing Selenium IDE. Once they are familiar and confident, go for Selenium RC, which is pretty much a automation driver for many other languages such as C#, Java, Perl etc. I use it with C#, porting the test is really easy.