My current Alert Dialog looks like the one of the right, I want it to look like the one on the left.

I think I can do that by changing the theme of the custom Dialog, but I am not sure if that is correct, and if it is so, then how to proceed? Is there anyway I can customly change the positive/negative button?
I dont want to create my custom dialog as the way the button show in alert dialog is perfect for me.
Something like the one on the right in http://developer.android.com/guide/topics/ui/dialogs.html
This is what I have done so far,
AlertDialog.Builder builder = new AlertDialog.Builder(LoginSignupActivity.this); LayoutInflater inflater = getLayoutInflater(); builder.setView(inflater.inflate(R.layout.newusersignup, null)).setTitle("Sign up"); builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {} //etc and my xml looks like
<TextView android:id="@+id/newUsersTxtName" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentTop="true" android:text="Enter your name" android:textColor="@color/white" android:textAppearance="?android:attr/textAppearanceSmall" /> <TextView android:id="@+id/newUserTxtPassword" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_below="@+id/newUsersName" android:text="Enter password" android:textColor="@color/white" /> <EditText android:id="@+id/newUsersName" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_below="@+id/newUsersTxtName" android:ems="10" android:textColor="@color/white" android:inputType="text" > <requestFocus /> </EditText> <EditText android:id="@+id/newUserPassword" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_below="@+id/newUserTxtPassword" android:ems="10" android:textColor="@color/white" android:inputType="textPassword" /> <EditText android:id="@+id/newUserEmail" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_below="@+id/newUserTxtEmail" android:ems="10" android:textColor="@color/white" android:inputType="textEmailAddress" /> <TextView android:id="@+id/newUserTxtEmail" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_below="@+id/newUserPassword" android:text="Enter your email" android:textColor="@color/white" android:textAppearance="?android:attr/textAppearanceSmall" />