I am unable to install window 7 on my computer

Your friend is right, Windows 7 is far better, faster and smarter then Windows XP. In fact, The producer of Windows XP is about to shutdown the Windows XP, perhaps we would not be able to use XP anymore once it is finished by Microsoft Corp.

Before, I answer your questions let me tell you the basic of installing the Windows 7 and the system requirements. You must have a boot-able DVD/Pen Drive to install Windows 7. But before using any boot-able drive make sure, your system meets the minimum system requirements.

Q-1. How was I unable to install window 7 on my computer?
Ans - There are many errors one might face while they install any OS on their system. You were unable to install Win 7 can't be figure out. Please be specific with the kind of error you faced.
Q-2. How can I install window 7 on my computer?
Ans - Very simple! Make sure your system meets thee minimum hardware and software requirements for Widows 7. Now get the boot-able set up files or drives and install it. Get help from some techie if you have no idea about it.
Q-3. Are there some special requirements to install window 7 on our computer?
Ans - Yes, There is a special requirements for ever edition of Windows 7, Windows 7 Ultimate is the best one and it needs high configuration.

1 gigahertz (GHz) or faster 32-bit (x86) or 64-bit (x64) processor
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)
DirectX 9 graphics device with WDDM 1.0 or higher driver

Q-4. Can I myself install Windows 7 on my computer?
Ans - Yes, you can but you should have a little idea about OS and system.

Q-5. If I install Windows 7 on my computer, what are other advantages of it when compared to it with window XP?
Ans - Perhaps! You're a bit late. After Windows 7 Windows 8 has arrived i market and people are now thinking of Windows 8 which is better then Windows 7. Same way, Windows 7 is the successor of Windows XP and it is far better then Windows XP. There are many unique features which you can't experience in Windows XP.

Q-6. Should I change window XP with window 7 or not?
Ans - If your system meets the minimum system requirement of Windows 7 then you should go for it. You'll love Windows 7.