Hy. I have installed windows 7 in C:\ drive and after than i installed windows Xp in D:\ drive.
But now when i start my computer it automatically start windows Xp.
in the C:\ i searched for the boot.ini it was windows xp written there also.
please reply as soon as possible.
Probably installing XP after Windows 7 messed up the boot files. you should install the oldest system first. I think you'll need something like GRUB loader. There are others but I'm not really into that.