In that case, I think that the cleanest solution is to (there are lots of threads with more detail; I'll try to link to one).
1) Build win7 onto the SSD with no other drives attached to the system. This ensures that the actual boot process starts from the SSD.
2) Use a bootable utility to mark the old drive as not bootable. So your system will never try to boot from it directly.
3) Set up the My Documents and My Everything Else folders to point to _new_ folders on the old hard drive.
4) Have each user copy his/her files from the existing location on the hard drive to his/her new My Everything folder. The reason for this is to make them marked as owned by the username on your new system. The usernames will have unique IDs different from the ones on the old system even if you make the names the same.
And various cleanups like backup the data that was copied and then delete it, delete OS stuff from the HDD, .... unksol's suggestion to backup and wipe the HDD is a pretty good one, in my opinion; more work but you end up with only files with good ownerships.