I have two instances of XP on seperate drives setup with the boot.ini file. During boot up I am given the option to select which OS to boot up and so many seconds to make the choice.
Two links that were helpful to me:
<A HREF="http://www.jsifaq.com/subI/tip4300/rh4397.htm" target="_new">http://www.jsifaq.com/subI/tip4300/rh4397.htm</A>
<A HREF="http://asia.cnet.com/zd/insight/software/0,39044822,39140825-39000221c-1,00.htm" target="_new">http://asia.cnet.com/zd/insight/software/0,39044822,39140825-39000221c-1,00.htm</A>
Google will probably return many more...
....WW (5.1)