formatting a HD without reinstalling windows

[memory]

My friend may be buying a new computer and he would like to take the HD out of the one he is using now and use it as a backup in the new computer. How would he go about formatting the HD without putting windows back on? It is possible isn't it?

 

[The_Other_One]

When the computer is up and running, simply find the drive under my computer, right-click, and format. Or there are also options if you right-click My Computer, Manage, and then Disk Management(of course I'm going off XP. I guess I should get more experience in Vista pretty soon )