I am using windows 7 ultimate presently I need 2 change my os to windows xp but I am unable to install xp in my pc due 2 this windows7 there is no problem of CD that contains xp what I have to do in order to install xp.
Please send me an answer
With Windows 7 Ultimate you can install Windows XP and still retain Win 7.
XP Mode consists of the Virtual PC-based virtual environment and a fully licensed copy of Windows XP with Service Pack 3 (SP3).
It will be made available, for free, to users of Windows 7 Professional, Enterprise, and Ultimate editions via a download from the Microsoft web site. (That is, it will not be included in the box with Windows 7, but is considered an out-of-band update, like Windows Live Essentials.) XPM works much like today's Virtual PC products, but with one important exception: As with the enterprise-based MED-V (Microsoft Enterprise Desktop Virtualization) product, XPM does not require you to run the virtual environment as a separate Windows desktop. Instead, as you install applications inside the virtual XP environment, they are published to the host (Windows 7) OS as well. (With shortcuts placed in the Start Menu.) That way, users can run Windows XP-based applications (like IE 6) alongside Windows 7 applications under a single desktop.
Make sure your PC\Laptop meets the requirements to run Windows XP Mode. According to Microsoft, if we want to run Windows 7, here's what it takes:
1 gigabyte (GB) RAM (32-bit) or 2 GB RAM (64-bit)
16 GB available hard disk space (32-bit) or 20 GB (64-bit)
But to run Windows XP Mode, it requires an additional 1 GB of RAM and an additional 15 GB of available hard disk space.