Well, i must say i' going crazy configuring SEF on II6. I downloaded and installed Helicon ISAPIRewrite3 FREE version. I loaded a generic HTTP.CONF like this:
#Fix missing slash char on folders
RewriteCond Host: (.*)
RewriteRule ([^.?]+[^.?/]) http\://$1$2/ [I,R]

RewriteCond Host: (www\.)?(.+)
RewriteRule (.*) /$2$
Then I patched the index.php on Joomla root adding these lines:
if ( isset( $_SERVER[ 'HTTP_X_REWRITE_URL' ] ) )
{
$_SERVER[ 'REQUEST_URI' ] = $_SERVER['HTTP_X_REWRITE_URL' ];
}
I set on configuration panel of joomla to use SEO and Mod_Rewrite.
I restarted II6 but only the home page appeared, the other pages went to 404 error, even if the address traduction si correct.

I follow this tutorial on the Helicon site: Link: Tutorial

Anybody could help me???

Well,
with Helicon Isapi Rewrite 3, you should be able to use the rules in .thaccess file without any modification.
Just if you are using their free version (which does not allow individual configuration files, just the one main), you need to add
RewriteCond Host: yoursite.name
before the other standard Joomla .htaccess RewriteConds to make sure the rules will be applied only to URLs for the Joomla site.

Also, make sure the Isapi module is listed among allow Isapi extensions. (if I remember right, that is not done by installer by default)

In any case, good luck. Configuration on IIS is not so trivial. (otherwise we would not ask 100 EUR to do it ;-D)