Vod

So I wanted to make another installation of windows xp. I tried to install it directly from windows. But the thing is, it didn't even asked on wich partition to install, and just copyed to installations files on the partition of my already running XP. It reboots to install the new windows, but I get an error message at the very beginning and I can't install it. So I install another Windows on a new partition and everything goes fine.
But now, I can't boot on my old windows. When booting, I get to choose between the Windows installation (wich bugs) and the Windows installed on the new partition, but not my old one.
I deleted the folder containing the files required for installation, but now, when I choose to boot the windows-to-install, it still tells me that it's going to install, but after this, all I get is a black screen with my mouse pointer.

Since nothing has been installed (just the installation files copyied on the hard drive), I believe my old windows hasn't been affected.

Now all I want is to be able to boot on my old windows.

In short:
1.Old windows (not able to boot anymore)
2.Widows in the process of installing, on the same partition as old windows (wich bugs)
3.New working windows on a new partition

Now I'm just able to boot 2 and 3 and I'm looking how to boot 1.

I hope my post is at least semi-understandable :/