When Converting PHP to ASPX, How To 301 Redirect Old PHP Files?

Moving client from another Web host and he ranks #1 in Google

[jastra]

We are getting a new client for our Web-based travel software. The client's site is currently hosted with a competitor and is integrated with that Web host's version of travel software. The site is written in PHP and on an Apache server.

But our software is written in ASPX, on a Windows server and using IIS 6. We will convert the current PHP to ASPX and then integrate our software into a subfolder.

The client currently ranks #1 in Google for some of his keywords. Obviously, we don't want to cause a drop in rankings when doing the changeover, and not 301 redirecting the old content is one of the best ways to do that.

My question is, what's the best way to accomplish the change to make sure that we can 301 redirect all those old PHP pages to the new ASPX pages?

Any other suggestions would be appreciated.

[marcel]

I think the easiest way would be to use something like ISAPI_Rewrite.

[jastra]

We are leaning in that direction barring some other workaround. But there's nobody here of our staff who knows regular expressions. Where's the best place to go to find people with those skills? We could eventually figure it out but we're up against a time crunch.