Error loading Windows when setting up dual boot

I have a computer running Windows 7 Home Premium (Advent SE 1101), is about 6 years old and is a basic model but it suits my needs, but I thought I'd set up a dual boot system with Windows XP as this would run old games that I have (I've tried compatibility mode with no success). I know how to set up a dual boot, but have come across a problem.
What I done first was partition my HDD, I set aside 10GB for the Windows XP, I then put in the XP disc and restarted my PC, the setup began and I selected my new partition and it formatted the partition and copied the files across etc, but when the point came for the PC to be restarted during setup it came up with a message saying. "PRESS ANY KEY TO CONTINUE..............ERROR LOADING OPERATING SYSTEM"
Now everytime the computer starts it comes up with that message, as its trying to load XP, so I can no longer access Windows 7. I tried to use the repair mode on the XP setup but couldn't make sense of it, I also tried putting in the Windows 7 disc to see if I could rescue my current OS, but no luck there either. I tried searching the menus to fix startup issues, but it wouldn't pick up either OS (Only the one on my Windows 7 disc), but I know my files are there as I could search for them, as it said to select an OS I would need to search for a driver, but no idea what one that would be.
Can anyone help, would either like to continue with XP setup if its simple enough, or failing that I'd like to just get my computer back the way it was before I started this.

Your simple answer would have been to run xp as a virtual PC with free virtual box as you don't have to mess with booting. For duel boot you always install the oldest Windows first as the old one won't understand a new version of boot loaders the new version will understand the old one. Installing XP has destroyed the MBR and boot sector. Do you know if you have a small partition that 7 boots from or not as it makes s difference but using fixboot, fix MBR should get 7 going

Offhand I am not 100% sure if Win 7 boots from a separate partition, but I can try the Fixboot option, how would I go about doing this?

Did you do a backup of your files prior of the attempt to install Win XP? If you didn't, do it now by placing your disk on another desktop or booting from a Linux USB flash disk.
You booted with the Win 7 installation disk and did a Startup Repair and it didn't find Win 7 on your disk?

Yeah after I started having the issue I put in the Windows 7 disc and tried doing startup repair, but it only found my disc drive (D:) but not my C: drive, I tried searching for it manually and it was there, but not sure what files I would need to select.
And fortunately I already have a backup of my computer for most of my files.

I'm not a specialist on this matter, but I think that Win XP made it's partition active.
Ask SIW2 for help https://www.sevenforums.com/members/siw2.html

I managed to fix it, I put in the Windows 7 disc and opened the Command Prompt, I typed in boot.exe/FixMbr and it worked, thanks to all who helped.

Congratulations. Please mark this treat as solved.