I have a Pal v9 PS2 with a 160 gb Samsung HDD installed

Just bought the network adapter a couple of weeks back from the local gray market over here in Mumbai, India. The damn thing cost me $90 US brand new (network adapter only), but I think it was totally worth it

Just finished playing GOW2 DVD9

Now trying the Titan Mode

These network adapter thingies are going really extinct or somethin so grab one while you can
I think you can use an external USB HDD and use
USBExtreme to boot games off of it, although am not 100% sure about it and I haven't really tried it. But from what I have heard, the games run fine but since the USB is only 1.0 (which is pathetic) the in-game movies will be skippy/choppy and the loading times MIGHT be increased but the game will run

, although am not sure of the compatibility of all the PS2 games coz never tried it myself
May be you can google for it. Also, I don't have any idea about booting DVD9 games off of the USB HDD using USB Extreme.