dual booting 7 and xp


if i already have 7 on a hdd and xp on another hdd, can i use easybcd to make it dual boot or will i need to reinstall either os?...currently i just plug the one i want to use in and unplug the other...
Plug in both HDDs, put the W7 one top of the HDD boot sequence.
Boot W7, Install EasyBCD 2.0.1
Add a BCD entry for XP, let EasyBCD auto-configure.
Job done.