i cant install ubuntu

Try using the Ubuntu Classic interface.

At the login screen, click on your username, then down the bottom you'll see a an icon to select the DE (Desktop Environment). Click on this and you'll get a pop up menu. Select "Classic", then type in your password and log in.

If this works better then you should open "Software Sources" and enable proprietary drivers if it isn't already, then open "Additional Drivers" and see if there's an proprietary driver for your video card.

On installing this driver you _may_ be able to change the DE back to Unity if you wish.

Further help would require knowing what video card is in your computer press <ctrl><alt>t to open a terminal or press <ctrl><alt><F2> to switch to a text console if you're still having display problems.

Enter or past this command into the terminal:

sudo lshw | grep -A 12 display

and copy the contents here.

To go back to the DE press <ctrl><alt><F7>

chris

can i install ubuntu 11.04
suggest me which type of version is good to my pc config

On your hardware, the latest version, Ubuntu 11.10 Oneiric Ocelot, should be fine. If you want the Ubuntu Classic interface, you cannot use this version, but you can use Ubuntu 2D which should solve video problems the same way Ubuntu Classic does, and you can use GNOME Fallback (after installing the package called gnome-session-fallback) which looks a lot like Ubuntu Classic.

I recommend testing from the live CD first to see if it works. This is not a perfect way to guarantee that there won't be problems, but it helps.

there is 1 error

Which error ?

"it seems that you do not have have the hardware requirements to run unity, please choose ubuntu classic to login screen and u will be using traditional environment "
i have tried it but it not works

Unity interface needs a graphic card (or GPU) with some 3D capabilities. So you have to use Gnome 2.3 (Ubuntu Classic) on your computer. What is your GPU ?
If you have a login screen, there is a menu allowing you to choose Unity or Ubuntu Classic. On 10.04 I used this interface.