jd01 - 5:05 pm on Oct 3, 2009 (gmt 0)

There's really no need to redirect any of the pages, in fact I recommend you don't.
This will Rewrite all the .asp urls to the php equivalent:

RewriteEngine on
RewriteRule ^([^.]+)\.asp$ /$1.php [L]

Using this nothing, including the links or URLs change from the front end. It stays exactly the same as it is now (or was yesterday :).

If you are having issues with the Query_String, you might need to use QUERY STRING APPEND:

RewriteRule ^([^.]+)\.asp$ /$1.php [QSA,L]

And I'm not sure if it's a typo or not, but you should have a space between the left side of your rule and the right... IOW: there should be a space before http: in your examples.