Makes sense to me ... .htaccess:
CODE
RewriteEngine On
RewriteRule ^/page.htm /new/page.htm [R=301,L]
RewriteRule ^/page2.htm /new/page.htm [R=301,L]
RewriteRule ^/path/page3.htm /new/page.htm [R=301,L]
To explain *why* you'd wanna 301 the pages: if you have existing, index-by-search-engine pages and simply switch them without the 301, you risk losing your indexed pages. It's a handy trick to return them with "301 - Moved Permanently" so they'll be reindexed on the new URLs immediately.