External USB HD and boot option

[zillah]

I have got external USB mobile HD 40 GB, If I installed two OSs , Windows on the PC's HD and Linux on the external USB HD.

Can I boot from external USB HD if I want ?

Do I need to be aware of any option in the BOIS to achieve this ?

If I remove the external USB HD, do I need to change BOIS again ?

 

[SHAWN]

Depends on the motherboard.

 

[zillah]

I have got intel motherboard support P4.

 

[zillah]

Any idea