[CentOS] Problem installing WordPress on CentOS

Hi,

I have a curious problem installing WordPress on a local LAMP server 
running CentOS 5.5. I have some other (dynamic) websites running on the 
same machine without problems. Here's what I did.

1) Create a 'wordpress' database in MySQL monitor.

2) Download WordPress, unzip it into /var/www/html/

3) # chown -R apache:apache /var/www/html/wordpress

4) Open Firefox on http://localhost/wordpress

5) Follow instructions (fill in database name, database user and 
password, etcetera).

And here's where things go wrong. When I click on "Begin installation", 
Firefox wants to "open" the file install.php by leaving me one of the 
two following choices :

a) edit "install.php" in GEdit
b) download "install.php"

I'm puzzled. Why doesn't install.php simply open as a page?

Any idea what went wrong here?

Cheers,

Niki