Update.
I have now tried the motherboard setup outside of any case, the problem is still there. I reset the BIOS and the pc started to runas per normal i set the bios up, rebooted and it got as far as the xp screen then shut down. Every time i restart it does the same sometimes it gets slighty further eg 5-6 secs more but it always shuts down before getting to the desktop. I cannot fathom this out, why would just changing the case cause all these problems? I am wondering about the power supply, could it be that it is not quite powerful enough? would that cause these symptoms?
Thanks for your help
Cheers
Martyn