There's a couple methods you can use to do this, but they both suffer from the same problem:
1. You can use Norton Ghost to transfer the partition (in various ways) like you talked about.
2. Partition Magic can copy a partition intact from one drive to another, including to the RAID 0.
The problem comes in if this partition contains your Windows installation. That Windows installation can't boot, because it doesn't have the drivers for your RAID installed.
If the partition is just a data partition, and you're booting from somewhere else, then it's no problem. You can copy the data partition from the old drive to the RAID, boot your Windows installation, install drivers for the RAID card, reboot, and when it comes back up your data will be on a drive letter just like before.
Generally, if you want to boot off a RAID, you have to reinstall Windows and install drivers for the RAID during Windows XP setup using F6.