My hard drive is clicking constantly and every now and again the computer just freezes or crashes completely, when I manage to reboot it Windows always identifies it as a hard disk problem. Before you ask yes I've gone through all the scandisk type solutions with no lasting succes. I think I'll have no problem in fitting a new hard drive but will Windows see that I'm installing the OS on the same computer or will it kick me out thinking I've installed a single version of Vista on a second computer
If the drive is not too far gone, you can always use a disk mirroring program like Acronis to simply mirror your old drive image to the new one.
Install new drive as seconday, run Acronis, image old drive to new one, shut down, remove old drive, go into BIOS, set new drive in boot order, reboot, presto.