Dual boot XP and Vista not working!

Hi!
Here is the situation: Laptop Acer Aspire 5050 that comes with Windows Vista Home Basic. H.D.D: 80 GB that has a hidden IESA partition called PQSERVICE (in the beginning of the hard disk, I'm mentioning this because I think it has something to do with my problem)

Vista is installed on C:\Acer
I installed XP on D:\, of course you won't be able to boot Vista at this stage.
You simply boot from the Vista DVD and choose repair your computer - Open CMD Windows - then type this:
X:\Sources> Bootrec /fixMbr
X:\Sources> Bootrec /fixBoot

The problem is the second instruction isn't working (fixBoot). I tried the same process on a Toshiba laptop and it was very easy. But on this laptop I'm talking about I'm getting a message that the file system isn't recognized.
The fixMbr is working successfully, but the fixBoot isn't. Could it be that the fixBoot is trying to write a boot sector on the EISA partition?

What should I do?
Vista is working by its own when I restore it from the CD. As soon as I install XP I can
only boot XP.