bootcd.iso problems

Hi,

I have opened bootcd.iso with ultraiso and added an img file to it, all well and good. I then wanted to save it out as a new.iso. When I then try and 'burn' this iso to a usb key and then boot up with it, it does not recognise the boot loader.

So my question is this. How can I re-save a modified version of bootcd.iso and still get the iso image to boot correctly. I think ultraiso does not recognise the boot sector correctly.

I am trying to make one iso that contains the bootcd and the image files all on one usb key to make it easier to restore the hard drive.

Thanks.