Assuming you're doing a clean install, it's pretty easy to use the installer's partitioner to set up a RAID (assuming you want mdadm software RAID). But depending on exactly what you intend to use this server for, RAID5 or even RAID at all may not be the best of ideas.
IMHO, RAID5 only makes sense for situations where maximum storage/dollar is the priority. If performance, or reliability, or ease of maintenance are higher priorities, then I feel other options usually make more sense.
RAID5 was more important in the past, when it was often the only practical option for acheiving the required storage capacities. However, nowadays you can get a 500gig drive for $100.