I would say the URLs that you provided are equivalent and generally
speaking, I would prefer to see the dynamic versions.

One of the reasons for that is that we can use the information
provided through the parameters to better understand what your site is
doing with those parameters. For instance, the URL
http://www.mysite.com/search.php?q=keyword  can give us information
about what is happening, it could even allow us to recognize that this
is a search form and perhaps let us attempt other keywords that might
lead us to content that we haven't seen for your site. On the other
hand, a URL like http://www.mysite.com/search/keyword does not give us
any information at all about what the "file name" is used for.

I realize that this is a fairly big change in the way that webmasters
think about "search engine friendly" URLs. I think it's important that
we are open about the kinds of problems that we have seen frequently -
and that we can give you tips about how to resolve some of those
issues :).

Hope it helps!
John