Lol...looks like you're in a bit of a problem there.
First of all, EasyBCD is not the bootloader, its not the bootmanager, and it didn't mess up your boot (at least not by itself). Anything it does, is because you
(the user) told it to. EasyBCD is just a normal program who's execution is over once you close it. It has no affect on the system whatsover at boot time. It is only what you
have done with
EasyBCD that messed up the boot.
The bootloader was written by Microsoft, and belongs to Windows as a small (but very essential) part of the system. The BCD (boot configuration data store) file is what EasyBCD operates on, and is what is responsible for storing the boot options (i.e. the boot entries in your boot menu at startup of PC).
Ok...now onto your problem.
First of all, we need to determine precisely what you have done to your system to render it unbootable. From the sounds of it, you can't get into either Vista or XP. Attempting to boot into XP you say gives you an NTLDR missing message. Ok...I've heard that one before (many times). The problem is, its unclear whether you used EasyBCD | Manage Bootloader | Uninstall the Vista bootloader | Write MBR to digress the MBR/PBR to XP versions (which are incompatible with Vista), or your problem is of another variety (such as just
a missing NTLDR). The difference is very important, because with one you will need to repair your Vista MBR, while the other one would mean you're just missing the NTLDR.
At any rate, a simple answer "yes" or "no" to the following question will produce the information necessary in order to determine one way or the other: Do you see a boot menu at startup when you turn on your computer, then
you select XP in the menu, and that's when
you get the error?
If not, it means you did indeed replace the Vista MBR with the XP one, meaning you'll need to run Startup Repair from the Vista dvd or our recovery disk to get it back. Once you can get into Vista again, it will then only be a matter of using EasyBCD 2.0 Beta
to delete and re-add the XP entry, letting it auto-configure, without changing where its pointed, and you'll have your dual-boot back.