I have to ask you to be a little clearer. Here are two quotes from you. The first says that you want to install Windows 7 on a different drive:
gigoe :
i have currently windows xp and i want to install windows 7 on another drive but if i want to do this i have to loose xp start up so my question is can i Start Windows XP without formatting 2 drives one after another
The second says that you want to install it on the same drive as XP:
gigoe :
dude it s another method but i don't want to install on another hard disk since its only data hard drive and its WD Green Intilipower so will make my OS little bit sluggish
So please make it clear. Do you want Windows 7 on a different disk drive from the one that has XP installed on it, or the same drive?
gigoe :
dud i got your point but is there any way to set 2 os selection option like i want which 1 to choose on start up
Any of the approaches outlined so far will let you boot to a choice of startups.
1) Install Win7 on a new partition on the same drive that has XP. Win7 will replace the XP bootloader, but will see that XP exists and offer you a choice when you boot up.
2) Install Win7 on a separate drive while the XP disk is still attached to the system. As above, Win7 will replace the boot sector on the XP disk, the installation process will see the XP installation and build a boot menu. If it doesn't, use the tool EasyBCD to add XP to your boot menu.
3) Install Win7 on a separate drive while the XP disk is disconnected. Then reattach the XP disk. At this point, you can either
3a) Choose the boot drive in the BIOS menu
3b) Use EasyBCD to add XP to the Win7 boot and make the Win7 drive your default in BIOS.
Unless you are already familiar with the BIOS, it's easier to use approach one or two. The Windows 7 installation should set up the boot menu for you.
Please back up your system drive to an external disk before installing 7 so that you can recover if anything goes wrong.
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Please just add an answer at the bottom of the page instead of using the "reply to" button. I type a lot of words and having them repeated in your post is a waste of screen space.