It is not really complicated to copy a partition to another hard drive or even to a RAID array (that is like a new hard drive for Linux).
GParted Livecd offers a copy possibility. There is also Clonezilla, that is dedicated to copy partitions or hard drives (look at the documentation page for its web site, please).
You need to verify that GParted Livecd detects the RAID adapter. I wouldn't expect any problem on this, because I see that this RAID adapter is already supported by Linux (technical specification). Nevertheless you can easily check this with the Livecd, if you already have the adapter + hard drives installed and the RAID array done from the BIOS or special bootable RAID-management software (I don't know the exact way this card needs to define the array). I understand that this needs unfortunately the server to be down, because the Livecd needs a system reboot.
After copy, you need to resize the partition to the new RAID space, to adjust the "boot" attribute to the new partition (you can do them with GParted livecd too) and to fix the boot loader from the installation cd.
*But: it is necessary to reboot into windows at least 2 times after resizing. So, you have to be sure that your system before resizing is healthy and bootable. You can resize it in a second step. Nevertheless, I understand that the new disk space is equal to the old one (146.8GB), so no resizing need.
However, I think to a few eventual problems that you need to investigate before proceeding.
In general, you must take care to not leave both partitions (origin and copy) on the system when booting into mswindows: in such a case the operating system will detect the new partition and give a new letter to it. After this, it will be rather impossible to boot from the new drive (raid). In this case, the easiest solution is rather to everything reinstall.
It is possible that the RAID drivers aren't present in the actual installation (this is true for xp versions where RAID drivers aren't installed by default, I don't know if this is true for the service pack 3 too). If so, you need perhaps to "repair" the system from the original medium (cd), and eventually provide a floppy disk with the driver. I know there is an issue in the case we want to change hard drive settings from "IDE compatibility" to "SATA AHCI" or "RAID".
Similar possible issue with the mswindows drivers for the new controller card. Perhaps you need to install the new Adaptec card in the system with no hard drives connected, and install the driver (I really don't know if this is the right way, if the card is plug&play; I see there are support documents in the product site). Please, try to find info in mswindows and IT/professional forums about the specific issues.
It is highly recommended to run the system on a UPS, because a power failure would be fatal during a resize operation.
-- Another idea would be to clone the entire hard drive in the new RAID (so that the entire partition table with bootloader is copied), then make it the boot drive, take away the old drive and fix the driver problems.
** In any case, you need to have a good backup before trying anything that modifies the partition table and the filesystem (professionals keep often double backup copies). In your case, you don't risk the original hard drive, because you won't write to it. Nevertheless, the backup is always needed because some hardware failure can occur any time in a computer system.
(Thread moved to the live media section)
*** It is highly recommended to backup any important files before doing resize/move operations. ***