How to dual booth a PC?

Just want to ask if somebody knows the step by step process on how to have a dual booth in a PC?
Currently I have a pre-installed WINdowS 7 in my laptop, now I want to make it in a dual booth-up but don't know yet if it's really working cause I never tried yet.
I want to have Windows XP in my unit, as my second OS. I want to have XP because I have an application to be installed in XP which is not working in Windows 7.
So guys would you help me with my problem related to dual booth up..
Thank you very much..
It's highly appreciated....

u need to install xp in another partition in which win7 is not instaled and dont remove the mbr portion and set win7 as first priority boot

as replied earlier just use other partition as secondary boot option
and it will be smooth and fine

U need to install the two OS in different Partition. Then only you can dual boot a PC after selecting your boot priority.

I am not so sure how to do this process but I want to know what is the benefit of a dual boot PC. If you have a dual boot, what will happen to the PC? Are there any disadvantages?

The only disadvantages is your hard disk storage size will be decreases since you need to make a partition for your dual OS.

it's just easy, just install your XP copy to other partition, don erase your current windows 7 partition, woila when you finish windows 7 will manage your dual boot.

First, you need to partition your hard drive or you can put two drives in your PC. Then, install Windows xp or vista at disk 1 or Partition 1. After installation, you can install windows 7 on the other partition or disk. Just put your installation cd (windows 7) and start up with the windows 7 installation disk.

You also can install it with USB but first you need to make it bootable. I think there are a thread on how to make Bootable USB.