I don't understand exactly what you are wanting to know or what you are referring to by simulation.
If you are asking about attaching additional storage with a USB HDD, you can do that.
If you are asking about booting Windows XP off of a USB HDD, you cannot do that. Windows will not install itself onto removable media. You can install numerous distros of Linux to removable media however.
I still don't understand what you mean by simulation. USB flash drives, USB harddrives, and flash media look like regular drives in Windows. They don't simulate anything; they are actual drives. You can use these drives for anything and use them as regular harddrives. You can't install Windows to them though.
If you can clarify what you are asking by asking some well-worded concise questions, I can offer you more assistance.