In WAM you can choose which pages to protect and which user/pass combination gets people access to which files. It's much more powerful & secure than the password program Prism mentions.
WAM will do everything you want and when it comes to hacks, WAM has the facility to use .htaccess to block IP addresses.
The other password program is here:
http://www.coffeecup.com/password-wizard/
But, if you want secure, robust protection of a members only area then WAM is you only MAN

WAM is here:
http://www.coffeecup.com/website-access-manager/.
As with all Coffeecup software, you can download FULLY working 30 day trial versions. So, I would suggest you download WAM and set it up on your server to see how magical it is. Unlike other trial software, the Coffeecup trial offering is exactly as the purchased version but limited to 30 days. So you can completely experience it and then if you are happy, simply buy it and carry on without having to reconfigure anything etc. - Sweet
Here's a brief comparison:
http://www.coffeecup.com/help/articles/what-are-the-differences-between-password-wizard-and-website-access-manager/
Best of luck and if you need any assistance with setting up either application, just ask.
Dave