As I remember (please correct me) using WinXP you are able to connect and disconnect mouse and keyboard without having any problem (like reboot).
I do not know why the cabinet has to be open - but connecting and disconneting mouse and keyboard should not cause any problem (why not just taking mouse and keyboard with you - too heavy load?)
No boot needed when connecting or disconnecting mouse/keyboard. Can add and remove usb as well and all is available under windowsXP.
Cabinet does not have to be open - simply unlocked. Customer requirement for after hours I/O unit.