|Sometimes booting and sometimes not booting can be that the drive is slowing down. Some bios' have a 'hard disk pre delay' (or words to that affect) that allows the drive more time to spin up. If you have that option set it to about 6 seconds.|
You are talking about the Vista computer, right? If so it should be fairly new. Most manufacturer's are too lazy now to have restore disks. They just have a restore partition on the drive, which of course doesn't do any good if the drive is bad. And I assume you don't have that since you have the disks. But you might check the manual to make sure. If by chance you have the restore partition you can boot to that and do the restore. Of course you'd be restoring to the old drive but you can try it and see what happens.
Otherwise it may be the size of the new drive that's the problem. It'd be helpful to know exactly what happens when you boot from the disks and attempt the restore.
Real men don't use AntiVirus; they just reformat