I recently bought two 128GB SSDs that I'm planning on adding (RAID 0) to a system I currently have on a 1TB HDD. I'm hoping to redo the disk space such that the SSDs act as the boot drive (only other items would be things I install there explicitly) while the majority of my system is on the HDD - documents, media, program files. Something like this:

SSD = [ OS | Explicitly placed programs]
HDD = [ Program Files | Media | Documents | etc]

I have an external drive capable of holding all the data I want to save, so the backup isn't too much of a concern.

What I'm worried about is how I should go about doing this - do I need to do a clean install on the SSDs, reformat the HDD, move things like Program Files/Users to the HDD, and then restore data (not full programs but things like saves)?

Should I be using one of the regedit hacks I've seen around to change the default install directories instead of moving program files and users? Should I have the actual folders on the HDD and symlinks on the SSD? Or is there a better solution?

Do I need to disconnect my HDD while doing the clean Windows install?