g1smd - 7:21 pm on Sep 21, 2007 (gmt 0)

>> If you redirect non-www to www, and old-URL.asp to new-URL.htm both must happen in a single redirect to effectively pass inbound link weight, etc. <<

A redirection chain is always best avoided.

Additionally, the file extension is completely irrelevant to indexing and ranking. You can have any extension you want.

I have worked on a site that moved over to using PHP, but the URLs still end in .asp as before.

Cool URIs don't change.