Some questions about triple booting 7/Vista/XP

Hi everyone, I have been dual booting Windows 7 and XP for several months now, everything is working great thanks to your excellent guide:
Dual Boot Installation with Windows 7 and XP

But now I want to add a Vista partition. Usually, I do some reading and try to do everything by myself, but the last time I fiddled with the partitions, I corrupted the MBR and lost a lot of important data, so now I thought that it's better to be safe than sorry.

The questions:
1. Can I just follow this guide:
Dual Boot Installation with Windows 7 and Vista
to install Vista when both XP and 7 are already installed?
2. Is there a chance I can damage the other partitions by installing Vista?
3. Is there anything else I need to know before I begin?

Now for some info:
I have a 1TB HDD composed of 2 500GB HDDs in RAID 0.
I have several partitions. NTFS, FAT32 and even exFAT. I will install Vista on a 45GB NTFS partition I will create.
I'm dual booting Windows 7 Ultimate X64 and XP Pro SP3 X86.
My system has an Athlon II x3 435 CPU with 4GB of RAM.

Thanks in advance for any help!

Good advice given above.

Why do you need Vista as well?

Wow, lightning fast replies!

can you post a screenshot of your current configuration, to enable us to see exactly what may need to be altered

I'm not sure what you mean exactly, you want my bcdedit command output? my bootmgr file location? Disk Management panel screenshot?
Anyway, as per Jonathan_King and theog's suggestion, I'll try to install Vista first and if there will be problems afterwards I will provide whatever configuration you'll require, if that's OK with you.

Jonathan_King: Thank you for the warm welcome :) I will do as you suggested and will report back.

[edit]

Why do you need Vista as well?

It's a long story... Nothing to do with running a specific application(s) though.

I have run into problems. I'm trying to install Vista x64 and I need to load my RAID drivers to do so, but while installing them I get this message:

"To continue installation, use the Load Driver option to install 32-bit and signed 64-bit drivers. Installing an unsigned 64-bit device driver is not supported and might result in an unusable Windows Installation."

I read that I can press F8 while booting the DVD and choose "Disable Driver Signature Enforcement", but I did that and the error message persists.

Moreover, I'm afraid that even if I'll get Vista to install and then after the first reboot I'll get a BSOD (it has happened when I installed XP until I found the correct driver and from what I read, there's a good chance that it'll happen with vista as well), I wouldn't know how to boot Windows 7 (or XP) again, and this is the ONLY computer I have access to - I will NOT be able to surf the web and ask for help If I botch it up.
What should I do? I'll appreciate any advice.

More info:
My mobo is an ASUS M4A78LT-M and thus has an AMD/ATI Raid controller. I believe there are no singed drivers for my RAID controller.
I have created store backup by running the command "bcdedit /export <filename>" and backed it up on a USB flash drive (as well as on my HDD).

From what I see on Asus web site, the F6 Sata Controller driver disk covers Win XP,Vista, Win7.

Yes, it does. However it simply does not work for my motherboard (does not show on the list unless the "hide ..." checkmark is unchecked), and aside from that, it is unsigned.
As I said:

I believe there are no singed drivers for my RAID controller.

(I tried all drivers I could find)

Make sure you download the latest drivers.
You may need to unhide in setup.

I did download the latest drivers, both from ASUS and ATI, none show up and if I unhide and try to install them, I get the same error message (I assume it means they are all unsigned).

I think I'll try to experiment some Live CD Linux or that ASUS Express Gate to get some internet connectivity regardless of Windows. If I'll succeed, I'll try installing the 32 bit drivers instead of the x64. Hopefully I won't do any damage that isn't fixable...