usb extreme/advance really sucks. its not really compatiible with games and its slower than christmas on loading games. In my opinion, no hdd is better than using a usb hdd on a ps2.
As for real hdd gaming, if you have a V12 or V13, you can inatall (or have installed) hd combo, or hd connect to allow an IDE hdd to be connected to your slim ps2. I would really recommend that you have hd combo installed for you. too many small points and its a better product than hd connect.
As for a "Network Loader", it doesn't exist. There has been a few discussions on creating one, but it has always fallen flat when it comes down to programming it.
If you need help, post a question in the
forums, not my PM inbox. Thank you.