Problems Dual Booting XP/Vista

I am fairly experienced with re-installing and dual booting systems....but...This is my last resort.I have scoured the internet for a possible answer but no one else seems to have this problem.
When i install Xp on one partition and then Vista on the other or vice versas at least one of them doesn't boot...actually it's not even in my boot menu.
In the xp boot.ini file I tried adding vista to the file manually which didn't work and the same with BCDedit in vista.

Now the current xp i have installed is a modified one called Xp crystal edition.I only downloaded it because i lost my original xp disc.i'm starting to think thats the issue...which is bad.i need xp!but vista is pretty....oh the dilemma...and ubuntu doesn't know what half of the components on my computer are,so i could not be bothered with any linux alternative.HELP!