I have installed Red Hat Enterprise Linux 5 (kernel 2.6.18-8) on HCL LX INFINITI POWERLITE 9100EP. Installation is successful. However X server fails to start.
Then I have downloaded kernel 2.6.26.6 and have upgraded using following command:
Make mrproper
Make makeconfig #as the X server fails to start.
Make dep
Make modules
Make CONFIG_DEBUG_SECTION_MISMATCH=y
Make modules_install
Make install
After this I have checked that bzImage and System.map were copied into /boot and the /boot/grub/menu.lst automatically updated with the 2.6.26.6 version.

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ON REBOOT, I HAVE THE FOLLOWING ERROR
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Booting ‘Red Hat Enterprise Linux Server (2.6.26.6)’
root (hd0,0)
Filesystem type is ext2fs, partition type 0x83
Kernel /boot/vmlinuz-2.6.26.6 ro root=LABEL/1 rhgb quiet acpi=off
[Linux-bzImage, setup=0x3000, size0x2304c0]
Initrd /boot/initrd-2.6.26.6.img
[Linux-initrd @ 0x37e9a000, 0x155b26 bytes]

Decompressing Linux… Parsing ELF… done.
Booting the kernel.
Ide_generic: I/O resource 0x1F0-ox1F7 not free.
Ide_generic: I/O resource 0x170-ox177 not free.
Red Hat nash version 5.1.19.6 starting
Hub 5-0:1.0: unable to enumerate USB device on port 1
Mount: could nto find filesystem ‘/dev/root’
Setuproot: moving /dev failed: No such file or directory
Setuproot: error mounting /proc: No such file or directory
Setuproot: error mounting /sys: No such file or directory
Switchroot: mount failed: No such file or directory
Kernel panic – not syncing: Attempted to kill init!

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I am using following hardware:
HCL LX Infiniti PowerLite 9100 EP

CPU: 1x Intel Core 2 Duo T7300 @ 2.0 GHz
MEMORY: 1 GB
STORAGE: Hitachi HTS541080G9SA00 80GB
NETWORK: 1x 10/100/1000 Mbps Realtek RTL 8100SCL
CDROM: MATSHITA UJ 850S
VIDEO: Intel GMA 3000, inbuilt with 965GM
AUDIO: Realtek ALC660
USB: 4 ports

You might just want to grab the current RHEL5.3 kernel(2.6.18-128.1.10). RH does things a little funny. Once a version is release MOST of the packages do not change major revisions. RHEL 5.0 came with a 2.6.18 based kernel and RHEL5.7(or whatever the last number will be) will still have a 2.6.18 based kernel. They do this in order to keep the system stable. Do not be fooled however, their current kernel is far closer to a .26 kernel(with their patches) than it is to a .18 kernel. Trying to put a generic kernel on RHEL almost always results in an inferior system.

thanx lazlow.
installing RHEL 2.6.18-92.el5 on the same machine gave me no problem.

Also you may want to use a better compilation method via i.e

make bzImage
make modules
make modules_install
make install

I don't believe make dep or make mrproper are needed anymore.