Mod-rewrite or other to redirect folders

Using the example from the Apache URL Re-write page modified just a bit

RewriteCond %{HTTP_HOST}   ^www\.example\.com [NC]
RewriteRule ^/(.*)         http://another.example.com/$1 [L,R]



http://httpd.apache.org/docs/2.0/misc/rewriteguide.html

would this allow me to host a www.example.com page as well?

Meaning www.example.com goes to an actual index.html page while www.example.com/* goes to the another.example.com/*

No it would not, it would redirect all requests for www.example.com to another.example.com.

If you want to redirect specify folders, you need to either list all as a condition, or come up with a regular expression that would catch what you want without catching things you don't want.

Do you just want www.example.com/folder2/* redirected to anotherhost.example.com/folder1/folder2/* ?

Or are there other patterns?

There are patterns.

I need /folder1/folder2/file.exe to match the same directory on the new server.

However if they go to the root www.example.com I want to display a message that they this domain is no longer valid and have them redirect to another URL.  SO

www.example.com/folder1/folder2/file.exe would redirect to
fw.newdomain.com/folder1/folder2/file.exe

While if someone goes to www.example.com, they would see a message saying:

The website you are trying to reach is no longer valid, please wait while you are redirected or click here.

and then they would be sent to www.newdomain.com/newpage.html

I want people to still get their files if they access the old url, but at the same time people going to the home page should be redirected.

What arober11 provide will do what you want.

Can I just put this within a <VirtualHost> tag?

Yes.