Ok I found a couple of problems which when solved fixed the reflash problem. Thanks to CoreDump for helping me on irc.
1. Ensure that the md5 sum for the image is correct: The md5 sum was out so redownloading it fixed that problem.
2. If you rename the zImage under windows check the extension under DOS. By default Windows hides the extention. Being a windows newbie got caught out by this one.
In dos you can see the extention, also you can get windows to show the extension in the preferences.
Hope this guide helps someone with similar issues.
Daryl