well it looks as though you accidentally wiped out your windows 7 files, I'm not sure if 7 can simply repair the install by replacing the windows file folders or whther your stuck doing a re-install
I'm relatively certain this is not the case. I believe XP just overwrote your boot manager, and you'll just need to make a few minor changes, which I'll help you with. Dual-booting Windows is a pain, though, because it hates being on anything but HD1 and partitions 1-4. Anyway, I'll offer you two solutions, in case the first doesn't work. Update if you get any errors.
Solution using Windows boot loader:
Go to the run dialogue and enter "sysdm.cpl". In the new window, go to the advanced tab, select "Startup and Recovery," and click "edit" on the window that appears. It should already have your XP details in it, and should look similar to this:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(*)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(*)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
Where * is your partition number for XP.
Add this to it at the bottom:
multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows 7" /fastdetect
If that doesn't work, try this line instead:
C:\="Microsoft Windows 7"
This should fix your problem and allow you to choose what to boot into once you restart (make sure you have a line that says timeout=30 or something similar to allow you time to choose what to boot into).
Solution using GRUB:
Windows 7 will probably be on hda1, but I'm not sure where your Windows XP installation is. Your configuration should look something like this:
default=1
timeout=10
splashimage=(hd0,0)/grub/splash.xpm.gz
title Microsoft Windows 7
root (hd0,0)
rootnoverify (hd0,0)
chainloader +1
title Microsoft Windows XP Professional
root (hd0,*)
rootnoverify (hd0,*)
chainloader +1Where * is your partition number - 1 (GRUB starts numbering partitions at 0, not 1).
Restart and you should be in the clear.