Are you sure you have the correct/current kernel headers installed?
What is the output of the following commands:
user@machine~]$ rpm -q kernel-headers
user@machine~]$ rpm -q kernel-devel
From your post, it looks like you're running 2.6.18-8.1.3.el5xen so, if things are configured properly, you should see "kernel-headers-2.6.18-8.1.3.el5xen" for the first command, and "kernel-devel-2.6.18-8.1.3.el5xen" for the second one.
If you're missing the kernel-headers and/or the kernel-devel packages(s) that's an easy fix; simply install them with yum:
root@machine~]# yum install kernel-headers
(or, if the kernel-devel package is missing: )
root@machine~]# yum install kernel-devel
I'm not sure which version of the driver you're attempting to install, but the latest appears to be 10.70.2.3 for the linux 2.6 kernels, according to Marvell's site (http://www.marvell.com/drivers/drive...o?driverId=153
Hope this helps.