If wiring isn't a problem I suggest you do this:
1) Setup your PC and put together your (command-line) version of MAME with the front-end MAMEWAH.
2) Follow these instructions to have Windows boot almost invisibly and straight into MAMEWAH:
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How to completely hide windows, and SHELL directly into a Front-End
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Changing Bootlogo - MAY NOT WORK ON CERTAIN PC'S
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There's two ways to get rid of that bootscreen.-
1. The safest way is to get a program and screen from the net
http://www.stardock.com/products/bootskin/And get a decent skin. Either google, or try this one:
http://www.wincustomize.com/download.asp?SkinID=1015&LibID=322. The second method. Caution BACKUP NTOSKRNL FIRST!
http://www33.brinkster.com/userxp/booteditor.zip-------------------------------------------------------------------
DISABLE STARTUP/SHUTDOWN SCREENS
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Change from default windows XP welcome screen to older style by going to:
Control Panels -> User Accounts -> Change the way users logon or off.
Deselect the "Use Welcome Screen" checkbox.
Get rid of the startup and shutdown messages:
1) Start -> Run -> Type "regedit" without the quotes.
2) Browse through to the following entry:
HKEY_LOCAL_MACHINE -> Software -> Microsoft -> Windows -> CurrentVersion -> Policies -> System
3) If there's a 'DisableStatusMessages' dword, change it to 1, otherwise right click, 'add dword'
and change it to 1.
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CHANGE DESKTOP BACKGROUND COLOUR
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Enter regedit and browse to this entry:
HKEY_USERS -> DEFAULT -> Control Panel -> Colors -> Background
Change this to 0 0 0 to get a black screen.
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DISABLE BALLOON TIPS
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To turn ALL bubbles off follow these steps:
1. Click Start, click Run, type regedit, and then press ENTER.
2. Navigate to the following subkey:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
3. Right-click the right pane, create a new DWORD value, and then name it EnableBalloonTips.
4. Double-click this new entry, and then give it a hexadecimal value of 0.
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CHANGING THE SHELL TO MAMEWAH
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Note: To do this automagically during startup in XP your computer may be a part of a workgroup,
but it CAN'T be part of a domain.
Here is the process to follow in order to set up your front end as a shell:
1) You must have at least 2 users with admin privileges
2) Open the user that will be auto logged in to the account that will be running your front end
as a shell. This user should have admin rights.
3) Set XP to automate the login process.
4) Click START -> RUN and type :
control userpasswords2
Deselect the 'Users must enter a username and password' checkbox.
5) Click Apply
6) Enter the user & pass you want to login with & click 'OK'
7) Click OK again

Configure your front end... this is not a trial run, so make sure it's the way you want it.
You can always get the explorer back, but it will take a minute or two to do so.
9) Open regedit and find:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\IniFileMapping\system.ini\boot
Find a string entry called Shell.
Change the first 3 letters (which should read SYS) to USR.
The path after USR will look different for your system, but it should appear similar to this:
USR:BLAH\BLAH\BLAH. This tells windows to ignore the system’s shell values and load up a shell
value on a user by user basis. If you don’t do this it will never even look for the shell value
in the current user key, meaning the next part won’t ever be seen.
10) Enter regedit and browse to this entry:
HKEY_CURRENT_USER -> Software -> Microsoft -> Windows NT -> CurrentVersion -> Winlogon
Should be a string entry 'Shell'. If not, create string entry 'Shell'. Change this to MAMEWAH location.
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3) You can use the menu built into MAMEWAH to shut down, return to Windows or re-start the machine, but you will need to extend the wires of your PC power button to the front of your machine or something and add a pushbutton or something.
When done you can have something that looks like this:
Forgive the quality of the video, it's an older post of mine.