Verified answer

Yea real easy! Just install the OS on the drive and plug it itno your computer wen its off. then follow these steps:

1.Turn computer on

2. on manufactuer page(ex:Dell) at boot up, hit the key given in the corner of the screen to enter bios BEFORE os boots.

3. In the bios navigate with Lft Rt Up Dwn arrows and enter

4. go to boot order and unslelect everything but External/USB drive (and primary hard disk if u want ur files....gut make sure "2" is next to it)

5. then Save/Exit and allow ur computer to boot up

6. DONE!!!:)

Ps: it is kinda slow but on Esata and SATA capable motherboards it should run smoothly

Certain motherboards have USB boot support, but you would have to read the motherboard manual to find out if your supports it.

The only problem is that it would be almost completely pointless to boot off an external drive. While USB has DMA or Direct Memory Access, it is not the same as would be on an internal drive.

To make a long story short, it would be a HECK of a lot slower, with high latency on reads and writes to the drive.

Dont listen to that first poster of course you can do it. just plug in the hard drive and turn your computer on and imediatly press ESC to load the boot menu and chose the hard drive from the list

Istalling an os on that drive is another story.

No. Windows Vista definitelly does not support it. If you have XP you might be able to get it to work but its kinda complicated.