Windows Fails To Start (DURING INSTALL!)

Hi folks,
I'm trying to install Win 7 on a self-build machine made from left-over parts. All starts well enough with the initial transfer of installation files (black screen, white bar moving from left to right) and then the 'Starting setup' (or something to that effect) screen appears for a second or so before crashing to black screen with the message:

windows failed to start.a recent hardware or software change might be the cause.to fix the problem:
insert windows installation disc and restart your computer.

Bearing in mind that windows has not actually even begun to install yet, this error is not particulary helpful- nor is STATUS:0X0000225 - an unexpected error occurred, well duh

Anyhow, first step was to check the install disk, booting from it in my laptop got to the main setup pages (choose partition etc) without any issue so unlikely to be that.
Next was to check my ram using the windows memory checker ( the only option available on screen), it passed fine but to be on the safe side I substituted ram proven to work in another current machine. Same issue and again the memory check passed successfully.
Next up was the hard drive. I'd like to use a 32gb SSD but to remove this potential cause I switched to a 320gb HDD again proven in another pc. Same issue.
Next I disabled the raid array and unplugged my three samsung drives (hey you never know) and still same problem.
On the off chance I removed all usb devices (including an internal card reader). Still no joy.
The only thing left to change now is my sempron 145 to a spare Dual Core Athlon I've got lying around but I specifically purchased the 145 for this machine on the basis of it's low power consumption (it'll be on 24x7).
This is driving me nuts as I can't even get far enough to meaningfully debug,any suggestions would be much appreciated!
Thanks!

Since you haven't tested the install media beyond where it actually failed, I would confirm the ISO hash or download another, then burn to DVD using ImgBurn at 4x speed.

If this fails, write the confirmed ISO to bootable flash stick using Universal USB Installer with Win7 in dropdown menu, then boot under USB, Removable or HD's.

Next try wiping the HD to clear the boot sector: SSD - HDD Optimize for Windows Reinstallation.

Next try resetting the BIOS to optimized defaults, set SATA controller to AHCI.

If all fails try moving HD to another machine plugged in by itself to try install, then SysPrep before moving back to target machine: SysPrep to move HD to another computer

thanks guys for your quick responses-much appreciated.kegobeer, I couldn't easily identify the motherboard last night but I have the manual so will update once I've tracked it down. gregrocker, great suggestions-I ripped the disk to iso using imgburner and used microsofts usb download tool to install on a flash drive. Unfortuantely this gave the same issue but is a lot quicker and more convenient.
Before pulling out the SSD again to try the boot sector suggestions , I tried switching out the 145 sempron for a dual core athlon and this actually got me to the partition screen (it was really late then so I quit while I was ahead).
To give some background the motherboard has been used with the athlon cpu before for a windows 7 install- I then replaced the athlon with the 145 and replaced windows with ubuntu about 6 months ago. I now need to go back to win7 so pulled out the ubuntu (ex win7) hdd and put in the brand new 32gb SSD. Hard to see how any trace of the previous windows install could remain-even a ramdisk would have been cleared by now surely after numerous full powerdowns.
Anyway I suspect that I can complete installation using the athlon- not ideal but I'll take any progress at this stage. I'll keep the thread open for a couple of days while I try to complete the install in case anyone has any theories.

Ok managed to get this installing using the athlon and my new SSD. Still no idea why the installer didn't like my Sempron but there you go. Thanks again for the help.