Woohoo I have finally got around to totally sorting out my XBOX and thought people might like to hear the tale to be re-assured that it is safe and simple.
My original setup was a UK XBOX with Enigmah and worked perfectly.
A mate of mine did the soldering for the flash as the points required are really small and alcolhol and drugs have given me the shakes over the years .
TIP : When bridging the two points for flashing the onboard BIOS don't just drop solder between the points as you will make a mess and likely screw up the mobo. Use two very small pieces of wire between the points (I used around 3-4mm of very fine single core wire)
The two wires from the Enigmah that need to be cut were extended (I have a switch to place in there for the future...) out from underneath the motherboard to allow them to be cut.
The XBOX was put back together (minus the top) and powered on. Evolution-X started up from the HD (With the original MENU.INI). Went to flash ROM menu item and cut the two wires.
FTPd using FlashFXP from my PC to the XBOX, changed directories to the ROMS dir and ran the flashbios command. This took a few minutes but had a nice progress display on television. Once finished my XBOX rebooted itself and went into EvolutionX again. At this point I know the BIOS flash worked as if it didn't the unsigned code that is Evo-X would not have started
At this point I tested original DVD movies, DVDR movies, Original UK XBOX games and some backups. I also tested running various applications from the HD to ensure there were no problems there.
Now comes the good bit.
I found(!?) a 45 gig IDE drive amongst all my junk and decided to use that as my new XBOX storage. Plugged it into a machine (I used a P2 HP Vectra) as a slave drive on the primary controller. Loaded up Windows and ran the XBOX HD Prepare utility that is freely available from just about anywhere. This zeros the drive out and makes the necessary changes for the partitions to be recognised - This took around FIFTEEN HOURS on the P2 so if you decide to use a larger drive, beware....
I FTPd my C:\ and E:\ drives off the XBOX for safe keeping and installed the new drive. If you power up the XBOX with the blank drive in it will give you a nice error as there is nothing to load. You can however boot from the EvolutionX CDRW/DVDR/RW and FTP the files back from your PC to the new drive. The format command was dead simple and quick (I was half expecting to have to wait 15 hours for the format but it only took a few seconds!!
I had no trouble getting this all up and running. At this point I have 18 XBOX titles sat on my hard drive and still have around 35 gig free....
The worst thing that could have gone wrong was the BIOS flashing. If it had failed for whatever reason all I needed to do was reconnect the two Enigmah wires that I cut and re-flash.
Yet another success story!
I didn't want to go into details about the commands that need to be sent to the XBOX as they are well documented and if you feel nervous about doing that then my recommendation is be happy with the original drive...