htaccess redirect question

[hofmax]

I want to completely redirect my site structure and I want to redirect the urls to the homepage until the new page is ready.

So suppose I have links such as http://www.mysite.com/chat/language=greek+user=new

http://www.mysite.com/AdvancedGuestB....php?gb_id=724

So I wanted to try to redirect the respective folder /chat or /AdvancedGuestBook and everything thereafter using regular expressions

for the first example I tried this:

RewriteCond %{HTTP_HOST} ^/chat*
RewriteRule ^(.*)$ http://www.mysite.com$ [R=301,L]

These are supposed to be permanent redirects.
Can anybody tell me what the syntax with regex is for redirecting everything after chat or advancedguestbook ?

Cheers!

[Basil]

Options +FollowSymlinks
RewriteEngine on
rewriterule ^chat(.*) http://yoursite.com/$1 [r=301,nc]