|First, is the hard drive recognized in the BIOS set up. If it is, make sure that it is listed as a bootable drive and that it is listed in the boot order. It is OK for it to be listed as second or third behind floppy and CD/DVD drives, but make sure the drives are empty (especially the floppy drive if you have one). If the old hard drive or a second hard drive is listed there, it may prevent the system from finding your boot sector. Also, was the new hard drive the only hard drive plugged in when you loaded Windows? If not then the boot sector may not be on the same drive and removing the other drive or changing any settings may also make the system miss the Bootloader.|
If it is recognized in the BIOS, use the install disk and do a start up repair, even if the bootloader was on a now removed drive, this should work.
If it does not work, use the hard drive mfg's utility to test the hard drive via bootable CD.
You have to be a little bit crazy to keep you from going insane.