I have a site with about 380 interlinked HTML files.. I have to rename all the HTML files to .asp and make sure that the existing links are alos updated. Some one told me that isapi plug-in can do this job easier that it it can redirect all .html files to .asp files Can any one help me in this? More information and links is much appreciated.
What type of server are you hosting on? If your on a Linux/Apache server with mod_rewrite enabled you can write a script to redirect the external .html links to .asp. If you have shell access to that server you could also write a quick shell script to rename and switch the links on the pages themselves. If you are on a Windows server you will need an ISAPI extension to handle the URL rewriting and some 3rd party application to mass replace .html with .asp in the files and rename them.
LOL, no one seems to be actually READING your question. What you want is ISAPI_Rewrite by Helicon Tech. It's an IIS snap in. I'm not quite sure what the regex you'll need to use for the wildcard redirecting, but they have an awesome forum.