Virus protection will probably work with RAID. However, backup programs
sometimes have issues with RAID. For example, if you check the Symnatec
support site, you will find that GHOST does not officially support RAID.
However, it does work for some hardware RAID configurations. If you opt for
RAID, do yourself a favor and test your backup software before you add a lot
of programs or data. Also, remember that just because you can make a backup
with a program does not mean that you can do a restore with the same
program. Test the software!