Vista Tutorial - FAT Partition to NTFS for Boot Partition

Hello everyone.
So results that after 3 weeks working fine my PC gave me only BSoD for all OS's load even with every F8 loading options of Vista x64.
This was I think due to some difficult and unworkable installation of ATI Catalyst Software.
So I decide, to do a clean re-install of both of my OSs. After having a pain to eliminate Partition on the DISC where Boot files were installed, since XP installation program was saying it could not access this HD partition, I succeed to do it by switching in Bios my Priority of HDD.

But my problem is not that. Here it is:
after eliminate all partition on Both HDD I partition again leaving on each Disc 1GB first partition for Boot Files.
So When I install XP Pro SP2 automaticly when I indicate to install on third partition of on of my DISC1, the program indicate that it has to format DRIVE C: (First Partition of DISC0) for some OS files (suppose BOOT Files) and automaticly format it as FAT, after that give me the option to quick format the Third Partition as NTFS where XP will be installed.
So now I have a FAT partition C: which indicate in administrative Tools > Disc Management is SYSTEM, eventhough in Explorer with View all Hide File active, nothing it's showed in this drive C:.
I want to Install now Vista Home Premium x64, and I think I read once that VISTA is the first OS not compatible with FAT partition.
Do I have to change this C: partition from FAT to NTFS, How can I do that and make sure to keep XP Boot File in good shape?

Also I'd like to activate PAE for my XP sonce I have 8gb RAM disponible, but I installed EasyBCD but when I start it it show error saying that I do not have Vista Installed. Before when my PC was working I try through EasyBCD in Vista to activate PAE but it did not show that I had XP installed. How does it work?

Thks in advance for your answers

Install windows vista on another partition than windows XP partition, and you will have a dual boot " Windows XP & windows Vista".

To convert c: partition to NTFS open "run" in windows XP and write the following:

convert c: /fs:ntfs

then restart your PC to complete the conversion process.

Thks Ahmad, but actually Vista is on different HDD so different Partition and I already tried convert c: /fs:ntfs after installing XP but did not worked.

I finally use SecureRescue with Gparted and have been able to Partition as I wanted all NTFS and 3 Primary on each HDD, but both HDD show much less capacity than before on my WD 500bg it's missing 34gb and on my Maxtor 160gb it's missing 11gb???? So far I only install XP x84 and I had to do it twice since first time it was freezing at the end of the start load. So I think my problem are not resolved at all!!!

Any Idea?