Transplanting a hard drive

I have an Acer computer with a bad motherboard. I also have an HP system with no HDD. I want to install the HDD from the Acer into the HP machine so I can recover my data. How do I get the system to boot to Windows since I am switching this HDD to a different OEM machine? Thanks in advance.

If the motherboards are similar you may not have big problems but you'll probably have to install the drivers for the new motherboard and may have to reactivate like the other poster said. Worst case it will blue screen. Try and see what happens. You won't hurt anything. Try putting it in a working computer or buy an external hard drive case and connect via usb/firewire/esata. If you don't have or can't borrow a working computer you can try a live linux cd. It will be more work and a little more complicated if you're not experienced with linux but it can be done.

I didn't mean to infer that in my previous post. I can see where I wasn't clear. Sorry. What I meant to say was that he can get to his files by connecting the hard drive to a working computer via usb, sata or esata but not booting off it.

If you wanted to boot off it the bios needs to detect it. If the bios detects the drive, any kind of drive, you should be able to boot off it. Like when you leave your thumb drive connected and you get the "system disk not detected" error. The pc was looking for the system files on the thumb drive. People boot off an external dvd-rom on netbooks that don't have optical drives all the time. I guess you could boot off an external drive if you have no other options but I don't recommend it cause it will be very slow.