So to get right to the point of this. What are the real differances between the two? I've read around that MySQLi(mysqli_connect) is more secure but slower, where as MySQL(mysql_connect) is less secure but faster.

But I am more or less curious about this. Should I switch to MySQLi? And if so, why?

mysqli_connect is accesing a class, a constructor and some resources. This makes it more secure (it has some security improuvements) but slower (it has to access some functions, to get you the real mysql connection)

mysql_connect it's a core function and it's just that. It's faster because it's accessed whithin PHP itself and that's it. It's "not so secure", because you just open the connection.

I use mysql_connect because if you have a well done site, it's hard to take advantage of mysql_connect security "issues". In fact, it's all about your code, and all about your thinking

I've never looked at the difference in terms of security, but functionality. MySQLi allows you access to features of MySQL 4.1+ which are not able to be taken advantage of via the mysql_ functions. If your knowledge of MySQL is sufficient and you want the added performance of more-optimized queries, then MySQLi is the only way to go (when compared to mysql_ ).