Should I keep my xp home on my current c drive and then have xp x64 pro on my new velociraptor drive with it partitioned to have photoshop and then a further partition to work as a scratch disk drive.
Yes have the other version of XP on the seperate disk not the seperate partition on the same drive as the 32bit.
Have you installed the drive yet?
If so then use diskmanagement to make two partitions on the new drive and format them.
Once done you will have two more drive letters
Bot from your XP64 CD and run setup it will find the partitions and ask where you want to install to.
Tell it the first of the new drive letters.
It should then instal and when you rboot it will give you a choice of which system to boot to Home or Pro.