Please answer the questions I asked you in detail so we have all of the pieces.
We also need the Partition Wizard bootable CD drive map and listings screenshot to see for sure - you used it to reconvert to Basic disk, correct?
But based on the installer's drive map you have somehow also converted System Reserved partition from Primary to Logical so that it can no longer be marked Active and thus loses System partition flag.
So boot into PW CD now to change the 100mb System Reserved to Primary: How to set partition as Primary or Logical.
Then rightclick>Modify it to Set to Active. Apply both steps.
NOw boot back into Windows 7 DVD installer to delete the last two partitions created by Win8 since it couldn't see any Active partition to install it's boot files upon.
Then create a new partition for Win8, format and click Next to begin install.
If Win8 again tries to create its own System Reserved boot partition, you'll need to delete it and then repair Windows 7 by running from it's DVD or Repair CD Startup Repair - Run 3 Separate Times
until it starts and has it's System boot files intact on the 100mb System Reserved partition. Then Win8 should see an intact boot partition to write its files for the Dual Boot.