actually, i think he meant to use HDD with hdloader to play game backup from hdd, not playing games with hdd feature.The hard drive for the PS2 is pretty useless too, as a few select number of games actually make use of it.
@TS.. NA still needed if i'm not mistaken, just google it, there's a lot of tutorial about installing HDD on old model PS2.
or get a new one, you can get new slim ps2 for a low price