Cannot start Windows but HDD works!!

My ECS K7S5A just died for no reason - I was surfing the net and the PC restarted but didnt show anything on screen. Meanwhile the Optical drives emitted a solid lit light and the motherboard and PSU emitted a burning smell so I quickly turned it off from the mains - the soft off options didn't work!!

I now replaced it with an Asus A7N8X-E Deluxe and a 500W Jeantek ATX Power Supply - the PC now boots up and shows the boot screen. Then once its established the IDE drive it shows the message of "We are sorry but Windows did not start properly......and I have the option to Start the PC in Safe Mode, with Networking and Command Prompt, Last Know good configuration and Start Windows Normally. ALL of these options keep cuasing the computer to restart and Windows doesn't even start!!

I put the HD into my sisters PC as slave and I can access the files on that drive without any problem. Its just I cannot boot into Windows on that drive, on my sister's PC or the one which I changed the motherbaord in.

Where does the problem lie and how can I get into Windows on that Hard Disk?

Tried doing that but on the setup, after loading all the system files into the RAM on that blue screen prior to FDisk the system hangs when it says "Setup is Starting Windows" - so I cannot even do that!! Now what??

I had a sneaky suspicion that my memory would be a little screwed over - how can I go about running memtest considering my current HD wont boot into Windows?

BTW for the record I have tried installing Windows onto another spare hard drive and while it managed to install I kept being greeted with BSODs so now I have a suspicion that the memory has been screwed over, or the processor, or possibly the IDE controller - which one do you think it could be?? More importantly how can I run the memtest thing in DOS and how do I get it?? The sooner I deduce whether its my RAM or not the quicker I can start diagnosing and getting my PC back up and running - I'm tired of working on a shitty little Duron 800 :x

Where can I get these Memtest Floppy/CD images - do you have any that you can email to me so I can make the disk?

Hello

You need to Install Windows XP agine
Coz you Change Motherboard& Clipset
But if u change RAM or Video Card or other Staff u Wouldnt need to Reinstall Windows XP