Android :: Relative Layout Height To Fill Remaining Space

I have the following layout in my xml file:

<RelativeLayout android:layout_width="fill_parent"
android:layout_height="fill_parent">
<FrameLayout android:id="@+id/logoLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
-- some images </FrameLayout>
<RelativeLayout android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="vertical"
android:layout_below="@+id/logoLayout">

Button 1
Button 2
Button 3
Button 4

</RelativeLayout>
<RelativeLayout android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="5dip"
android:layout_alignParentBottom="true">

Button 5
</RelativeLayout>
<RelativeLayout>

Maybe I didn't do it in the best way. What I want: have the Layout that contains the 4 buttons to use the entire space between the top and bottom layout, and I want to have the button equally arranged in the layout. Something like this:
http://img16.imageshack.us/i/androidq.png/

I add the whole layout code:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/background">

<!--The header of the page-->
<FrameLayout android:id="@+id/logoLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<ImageView android:id="@+id/logoBackground"
android:src="@drawable/logo_background_small"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>

<ImageView android:id="@+id/logoImage"
android:src="@drawable/logo_small"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="left"
android:gravity="center"
android:padding="3dip"/>

<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/tracks"
android:layout_gravity="center"
android:gravity="right"
android:textSize="22dip"
android:textColor="#ffffff"
android:padding="3dip">

</TextView>
</FrameLayout>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:orientation="vertical"
android:layout_below="@+id/logoLayout">

<Button android:id="@+id/btn1"
android:layout_height="wrap_content"
android:layout_width="250dip"
android:drawableLeft="@drawable/img_small_btn_look_around"
android:background="@drawable/main_long_menu_button"
android:text="@string/btn1"
android:textSize="18dip"
android:textColor="#ffffff"
android:layout_marginTop="20dip"
android:onClick="btnMyTracksOnClick">
</Button> <Button android:id="@+id/btn2"
android:layout_height="wrap_content"
android:layout_width="250dip"
android:drawableLeft="@drawable/img_small_btn_look_around"
android:background="@drawable/main_long_menu_button"
android:text="@string/btn2"
android:textSize="18dip"
android:textColor="#ffffff"
android:layout_marginTop="20dip"
android:layout_below="@+id/btn1">
</Button>
<Button android:id="@+id/btn3"
android:layout_height="wrap_content"
android:layout_width="250dip"
android:drawableLeft="@drawable/img_small_btn_look_around"
android:background="@drawable/main_long_menu_button"
android:text="@string/btn3"
android:textSize="18dip"
android:textColor="#ffffff"
android:layout_marginTop="20dip"
android:layout_below="@+id/btn2">
</Button>
<Button android:id="@+id/btn4"
android:layout_height="wrap_content"
android:layout_width="250dip"
android:drawableLeft="@drawable/img_small_btn_look_around"
android:background="@drawable/main_long_menu_button"
android:text="@string/btn4"
android:textSize="18dip"
android:textColor="#ffffff"
android:layout_marginTop="20dip"
android:layout_below="@+id/bt3">
</Button> </RelativeLayout>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="5dip"
android:layout_alignParentBottom="true"
<Button android:layout_width="90dip"
android:layout_height="wrap_content"
android:textSize="20dip"
android:textColor="#ffffff"
android:layout_alignParentLeft="true"
android:background="@drawable/sett_menu_button"
android:text="@string/back"
android:layout_marginLeft="3dip"/>
</RelativeLayout>
</RelativeLayout>