If you have an external HDD then just plug it in your USB port on the computer then use WinHIIP. I've used HDL_Dumb, but it didn't work so well. WinHIIP is pretty self-explanitory, you just select the ISOs you want to load on the HDD and it will do it.
If you have an internal HDD there is a simple solution. Just get an adapter like this: http://www.newegg.com/Product/Produc...82E16812156101
It's a IDE-to-USB adapter. It's tedious to open up your PC case and have to reboot the computer to install internal HDDs. So you just use that adapter and it turns it into an external drive. It also helps when a game doesn't work with HDLoader. You use that same adapter and plug your HDD into the USB ports on the PS2 and try it with USBAdvance. I've heard that SOCOM 3 works with USBAdvance (it doesn't work on HDLoader). I'll have to try it out and see...
US/NTSC V5 - Matrix Infinity v1.75. - Network Adapter - WesternDigital 80GB HDD - CodeBreaker v9.2