Since windows 2003 `requires' 128MB of RAM at least, I installed it on a machine with 96MB. This takes some modifying of files on the CD, but after that it runs quite fine. I have seen a lot of people ask about how to do this, so I wrote it down here: Windows Server 2003 with less than 128MB RAM.

As of yet, I haven't found a free app that can alter files in ISO images, but I'm still searching for one.