Transferring projects from an older HDD to a new HDD

Nope at least not to me is there a better way to do it. Just mount it temporary in the new computer providing you can read the disk drive (which should happen) and copy the files to the new harddrive where you want them (or the harddrive you want them on).
 
Afterall there are much slower ways to do it, so depending if you want to make DVD's for all the projects and then store them and put into the DVD drive of your new computer and read them which may take a few days, or like stated above and take an hour or so to copy everything.

Network the two machines?

You just need something to carry the bits from one machine to the other.  Peronally, I use ants.
 

 
HTH.

The only thing is one hard disk is the Master and the other is the slave. I have not done copying in a while but make sure the drive you put in is set the correct way, or take out one of the existing drives that you will be sure not to use and make your old drive the same as that drive - whether a master or a slave depending on which Interrupt Channel it is put on in the computer.
 
Ah which reminds me that I bought a second drive to put in my new computer and I have not done that yet. I know that probably the DVD is the master on one Interrupt Channel and the Hard Disk already in the computer is the master on the other one. I just have to make the new one a slave setting hard disk and put it in on either Interrupt channel SATA whatever.