Installing new hard drive without format?

I don't understand your questions. You should only have to format and reinstall when installing a new motherboard.

If you already formatted before hand, then you lost the files.

which drive did you format, the new one or the one with your data on it?

So basically what you should have done is remove your original drive (with your data on it)
install the new drive formatt and install your OS
after thats done turn off install your old drive as a slave and power it up and your data will be on D: or E: or whatever comes after your optical drives..

Ok I'll try to clear things up sorry.

I was running out of space, so I went and picked up a WD320GB Blue, I installed it, and I had to format the NEW drive, my old drive still had everything on it.

Okay, then you need to either back up old files by burning to a disk or by having both drives connected, and booting into the original and then copying the files over to the new drive, then formatting the old drive.

I don't know what you mean by activating a drive.

ok as long as you did not format your original drive
So basically your going to install your old drive as a slave,for sata just hook it up and make sure to change your bios to boot from the new drive if it has that option

well....plug the new drive in.....format it....give it a drive letter.....then dump all that you need from the old hardrive.....pull it out for safety......start the vista reinstall on the old hardrive.....after it's finished plug the drive you copied the data to and that's it

@Halifax, before I could use my new drive, I had to go into my computer, format it and give it a letter

@Diabolical, yes it is, but before I could do that, I had to format it.

@ghozt, is that possible? I'm going to be reinstalling Vista on my old drive, as it reformats when you reinstall anyways. So the windows files will be on my old drive and I won't be able to boot?