Changing Server Platforms

[markdamo]

We are about to change our website from Coldfusion to asp.

Has anyone in experience in changing their websites platforms, and how it effects you search engine rankings.

Or whats the best way to deal with people still trying to access old coldfusion pages?

[mdoigny]

Keep the old site running with redirects to equivalent pages in the new system.
Spiders will see the redirect ("MOVED PERMANENTLY") and will update their database accordingly and you won't lose any page rank.
You will have to keep the old system for a very long time (months) for in case other sites are pointing to old pages.