Can't install a second copy of Vista (Acer 5920G)

Hello there, I got an Acer 5920G. I am very pleased with this machine specs-wise (T7500, 8600M GT), the only gripe was the low ram it initially had (1gb) but with the current prices I bought 2x2gb to upgrade it.

All went well and I wanted to make a fresh install of Vista Ultimate 64bit to utilize the 4gb to the max.
The laptop's OS is Windows Vista32 Home Premium and I do not want to get rid of this as the laptop is used by my parents too and they want to stick with it. But ont he secondary partition (D I want to have my own OS that is unaffected by them. Up until now I had WinXP because with 1gb RAM Vista was crawling.

So now What I want is to have a Dual Vista setup with Vista 32 home premium and Vista 64 Ultimate at the same time. The problem is, when I install the second copy of Vista (64bit ultimate) on D:, after the installation is complete and it goes to boot from the first time I get an error and it doesn't boot at all. No choice between the 2 vista installation, simply nothing works and I am forced to use eRecovery...

I really don't understand why this happens. I was under the impression that Vista use their own boot loader (different from XP) so having 2 copies of vista should make it easy. I was hoping that even if it wasnt totally automatic (to give you the 2 choices in a menu at boot time) it would boot to the last installed version of vista and I could fix the menu with EasyBCD from there... but it is a no go...

What's more strange is that the error it fives is Grub error 17 or something.....what the hell does Grub have to do with this? I thought Grub is a linux (or anyway non-windows) boot loader for multiple OSes... Does Acer have something to do with this? (due to their D2D recovery system maybe they use their own bootloader based on Grub?)

It is funny that I can setup my laptop to use Vista and XP, but not Vista32 and Vista64... can you help me understand what is going wrong and how to fix it? Or else I am stuck with XP for my personal OS, which is not that bad, but I'd liek to use Vista...

I managed to get it working with vista 32 and 64 in dual boot, but the procedure was painfull and stupid, so I'd like to give you the info in case you can understand why this happenned and this could help me when I want to do a re-install...

Well, during the Vista64 installation (vista32 already installed) whenever the system restarted I could catch a glimpse of hte boot loader that had 2 choices for OS (the 32 one and the 64 being installed) but quickly chose the ongoing installation and went on. When the isntallation finished though, the last restart gave me a no-boot and the same errors as before. The boorloader that gave the error seemed to be named GRUB4DOS.

The way I see it, for some reason my vista64 installation, before the last restart seems to replace the vista boot loader with some version of its own based on GRUB and this screwes everything.

What I did to fix it, was start Acer eRecovery from the DVDs, which restored my C: Vista32 partition and booted into it. Then I loased EasyBCD and created an entry on the boot loader for the Vista64 on D: . Everything worked fine and now I got a dual boot machine.

The question remains though....are there different Vista DVDs, and mine has this strange behaviour? If I get another DVD it could possibly not do this thing with the GRUB bootloader?

Right now everything works perfectly, but If I need to re-install my Vista64 (which I will at some point, just to freshen the system) I will be foreced into the same procedure and to bring the Vista32 installation to default settings for no reason (plus I wouldn't want that at all...)....so I'd like to see if there is a sensible explanation about this and a way around it....

I might add here that I tried repairing with my vista DVD and even though it did detect a startup problem, it actually did nothing to fix it.

In my opinion the most efficient way to solve this problem would be a way to bootfrom a CD and tweak the vista boot loader somwhow without being into windows. If for example there was an application like EasyBCD that could run from dos, or anyway some kind of vista boot editor (even command line based) that you could run by booting into dos from a win98 boot CD or something, I could fix the boot loader there would be no reason to use acer eRecovery which essentially the only thing that offers is accessibility to EasyBCD but at a great price (about an hour wasted and also it forces me to "reset" my vista32 installation)

I actually tried using a Super GRUB boot CD to maybe boot into windows so I could use EasyBCD from there....but the only "windows" partition that would work was the D2D recovery of acer lol.

I am not familiar with LiveCD, can you explain what is is please? I get an idea from the name, but some more information would be helpfull It seems like it could do the trick...