The Maxtor DiamondMax series is highly recommended and appears to be the best for the HDloader. You simply take a standard IDE Hard Drive (Either the official one, included with Final Fantasy XI) or a 3rd party PC Hard Drive using an IDE Interface.

You dont need to open your PS2 (Voiding your warranty), or sticking anything silly into it to make it read stuff. How do I install it? Do I need to open my PS2?

The HDLoader is a piece of software much like the kind you'd find at Gamestop or Electronics Boutique, that allows you to copy your original PS2 games onto a standard hard drive, to greatly decrease the time it takes to load your favorite games, as well as provide safety and security from your original game CD's and DVD's becoming unreadable due to damage (Perfect if you have younger people who insert and remove the discs themselves.) Also a lifesaver for people suffering from dreaded disc-read-errors or laser problems which can cause freezing, skipping, or problems within games (An example being the street textures in 'Grand Theft Auto 3' being invisible.) Seems to be one of the top questions going around.

Download hd loader ps2 fate