It would have helped to have the Disk Management screenshot requested so we can see what the config is.
Absent that, unplug the XP HD, plug its data cable into Win7 HD, make sure it remains set to boot first in BIOS setup.
Now mark the Win7 HD Active: Partition - Mark as Active (Method Two)
Now from the DVD run Startup Repair - Run 3 Separate Times
until Win7 starts and holds the System Active boot flags in Disk Management.
You can now plug back in the XP HD to access it's data from Win7 explorer, or boot it if needed by tapping the Acer F12 one-time BIOS Boot Menu key at boot.