If you want to have a loo into your initrd image, see what is there in it then you can do the following.
Create a folder called inirrd in your home folder, Copy your present initrd to the home folder
$ cp /boot/initrd.img-2.6.28-15-generic ~/initrd
(your initrd version might be different).
The initrd image by default is a gzip image, thus it has to unzipped first.
To determine the file format you can use the command "file".
~/initrd$ mv initrd.img-2.6.28-15-generic initrd.img-2.6.28-15-generic.gz
~/initrd$ cpio -i < initrd.img-2.6.28-15-generic
If every ting goes fine, the contents of initrd will be present in your folder,initrd now, check it by running "ls"