Question: Does anyone know if I can install normal 2.5" SATA drives inside an HP DL360 G5 server? Right now it has 6 72GB SAS drives. I am looking for raw storage for my files SAS performance in not required.

Answer: 
SATA drives always work when connected to a SAS controller, by definition.

Minor correction - the SATA drives must be SATA2 or newer (3Gbps) -- from comment below.
Few times I had a problem with SATA drives inside Proliant servers where under Linux drives were detected as PATA.

The solution was to turn off Auto mode for hdd in BIOS settings...