Triple boot :installing RHEL5.5 (Centos 5.5) ,Win XP and RHEL6 beta

[McKinon]

Hi As a newbie here I installed RHEL6 on my laptop,a Windows XP was already installed before installing linux,I can boot both OS without problem, Here is my problem, as It seems that the wireless is not working and I wanted to install Centos 5.5 or RHEL 5.5..As checked on linux forums about multiple boot, it seems that there are some problems to boot all OS...I need your advice to avoid boot problems with 3 or 4 OSs.
Here is the info about fdisk-l

Device Boot Start End Blocks Id System
/dev/sda1 1 9689 77826861 7 HPFS/NTFS
/dev/sda2 9690 60801 410557140 f W95 Ext'd (LBA)
/dev/sda5 9690 22437 102398278+ 7 HPFS/NTFS
/dev/sda6 22438 37748 122985576 7 HPFS/NTFS
/dev/sda7 60148 60540 3145728 6 FAT16
/dev/sda8 * 37749 37761 104391 83 Linux
/dev/sda9 37762 50503 102350083+ 8e Linux LVM
/dev/sda10 50504 50634 1048576 83 Linux
/dev/sda11 50634 50765 1048576 83 Linux
/dev/sda12 50765 51278 4120576 83 Linux
/dev/sda13 51278 57064 46475264 83 Linux
/dev/sda14 57064 58110 8396800 82 Linux swap / Solaris

Partition table entries are not in disk order
++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++
Windows is installed in sda1, the boot partition of RHEL6 is on sda12,
root in sda13 and swap on sda14.I will format sda8,9,10 and 11

I have installed RHEL5.5 before and got partitions messed up and want to reinstall RHEL5.5.. or Centos distro..can anyone tell me what I have to pay attention to when installing the RHEL5.5..
Shall I install the boot loader or don't install it and later go to /boot/grub/menu.lst and change some variables..if yes what do I have to change..
Do I have to change anything in fstab in /etc/?

Don't laugh at me please ,I am a newbie in Linux and trying to learn it..

[devils casper]

You can install another distro in any partition. If you don't change partition structure ( create/delete partitions ), nothing will go wrong. There is no need to create another SWAP partition. Installer will detect existing SWAP partition and use it.

Installer of RedHat based distros ( Fedora, CentOS, RHEL etc. ) do not detect other installed Linux distros. RedHat installers detect Windows OS without any problem. It doesn't matter if you install GRUB of new distro or not. You will have to add edit grub.conf file to add an entry of missing OS.

You don't have to change anything in /etc/fstab file. Install new distro along with GRUB. Boot up new distro and mount /boot partition of RHEL6. Open its /boot/grub/grub.conf file and copy first title block ( first title, root, kernel and initrd lines). Save that block in grub.conf file of newly installed distro.

[Rubberman]

Myself, I'd just install CentOS 5.5 and run WIndows and RHEL B6 in a virtual machine. Gee, that's what I do already! Who'da guessed?