You can even try to reinstall grub after booting from live CD .

Your system might be hitting this :

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=51306

let me know

well xorg.conf and output of commands 'lspci' and 'lspci -nv' .

I agree with Karsten Wade . However even if the inhouse staff is competent enough to push in features for the upstream, when it comes to getting those features backported to RHEL, you will have to be a RHEL customer. Also the flip side of using CentOS is patching the system with critical security erratas which come in Centos only after a RHEL minor release ( like RHEL5.1 , RHEL5.2 ) and for which you might have to wait for like 6 months. Same is the case with critical bug fixes for which you can get hotfixes if you are using RHEL. For all mission critical applications I would strongly recommend RHEL .

forgot to mention . Another way is using winbind and kerberos.

http://kbase.redhat.com/faq/docs/DOC-3051

This should work too. kbase.redhat.com is a nice place to check :) .

Well I am afraid your query is not very clear. Its always good to put detailed queries. However may be you are looking for something like this :

http://kbase.redhat.com/faq/docs/DOC-3639

let me know.

You might even want to consider using Logical Volumes (LVM) as it will make your life easier when it comes to resizing your partitions . You can do it on the fly without unmounting the filesysystem and its simple too . So what I would suggest is

/boot ----> 200MB

/ -----> on LVM ( You can start with 5 GB and later increase )

/home ------> on LVM ( You can start with 10G )

There are a lot of other great things you can do with LVM . For more information check :

http://tldp.org/HOWTO/LVM-HOWTO/