Would it be ok to mirror SQL Server rather then have a RAID 5 configuration?

ALL of my SQL Servers are either completely RAID 5 or have the data RAID 5 and the logs mirrored. My current situation deals with a printing software from DocuCorp. The software uses both SQL Server and flat files. The majority of the data is archived insurance forms that after a year will be about 18GB in flat file format. The actual SQL Server data will only be about 1/2 GB after one year. I am contemplating two configurations on the server. RAID 5 for the flat files (5 - 9GB) drives and either a second RAID 5 or mirror for SQL Server, the O/S and the printing software. If I choose RAID 5 for the SQL Server partition, I can only go as small as 3 - 4GB drives. If I choose mirroring, I can have 1 4GB drive with a 4GB mirror.

Would there be a performance hit by choosing mirroring over RAID 5 for SQL Server? Note that SQL Server will never get that big. Two databases will exist. One is a database of pointers that point to the flat file records and a second is a database containing insurance policy forms.

Thanks in advance for your input. Dave Holtz