SEO Friendly redirect and ShopSite

[royhink]

I've taken a subset of products from our main website and built a new site around them, and want a SEO friendly redirect so that I don't lose any ranking. If there are any SEO gurus out there that can advise, I'd sure appreciate it.

Since it is redirecting to a new site, I'd like to have an intermediate page that "introduces" the new site before the redirect. FYI, the old pages & products all have .html URLs.

The SEO pundits say that it must be a 301 redirect, can't have "id=" in the query string and should not be a javascript redirect. This certainly limits my options!

I am considering building an .htaccess file with a huge list of old URLs pointing to the new URLs. This would not give me my "introduction" page, however.

I could rename all my files to .php, wait for Google to re-index them, and then use a php 301 redirect. I might lose my rankings in the process, though.

How have others done this? All help appreciated, Thanks.

Roy