Theres two ways of doing RAID, software and hardware.
Software is a simple case within admin tools > computer management.
Just select the two drives and RAID from there.
)ALL disc's must be dynamic.)
Have a look here for further info
Hardware is basically BIOS control, now this isn't your normal BIOS but the BIOS of a RAID controller card. Many newer machine can do RAID on SATA out of the box.
For RAID 0 or 1 (Stripped or Mirrored) both drives need to be tha same size and speed, so you 300's would work well.
ALL of my servers are setup with RAID 1 for OS and RAID 5 for data, except my main ERP (big database) server which is setup with 4 pairs of RAID 0 drives. Tese are all hardware driven.