First off welcome to the sevenforums! ccwildcard
You are in a bit of fix there! First off if you delete the former Vista C primary neither XP or 7 will start up! The main boot files are located on the now seen by as D primary. Apparently you first saw an install of XP following Vista by the looks of the setup there.
In order to see a working dual boot of XP with 7 now you would need to follow a few steps I can outline for you here. But that will mean another slight change in the way things are setup.
1)You have two options of first seeing a second 7 installation on the first primary originally used by Vista. Or you can backup the two primaries and delete both the Vista and 7 primaries in order to see one larger new one for a fresh install of 7.
2)If you elect the later once you have the new primary created and formatted in order to be ready for use you first perform a repair install of XP in order to see the new mbr entries along with the new boot files placed at the root of the new C drive. How to Perform a Windows XP Repair Install
3)Once XP is up and running again following the repair install which will preserve the existing XP installation you can then install a fresh copy of 7 on the new primary then becoming the default OS as well as seeing XP added into the 7 boot loader seen as "previous version of Windows".
The BCD editor tool can be downloaded separately in order to rename that to XP Home or Professional depending on the edition. The free tool will also work on Windows 7 as well as Vista for both 32bit and 64bit RCs. System Tools - BCD Editor
To rename the previous versions item you simply click on the "set descriptions" button and enter the new name that will be seen on the 7 boot options screen. You can also set which will be the default OS as well as the amount of display time as you can see how that looks from the image on the download page there.
If you elect to save time by seeing the second copy of 7 installed on the existing first primary you can elect to reformat the now C primary in order to see the first removed. The BCD editing tool also sees the delete option for removing the entry for that as well.