I might seem stupid but can anyone explain to me what a RAID controller is and how it works? thanks a lot.

RAID = Redundant Arrays of Inexpensive Disks. A RAID control is used to set up and control the Array. The array can have many difernt settings. Strip set Mirror Strip set/mirror RAID 5 ..... So on and so forth. here is some info on RAID http://peripherals.about.com/library/weekly/aa082300a.htm

raid on a home pc = more trouble than its worth.

A raid mirror on a home PC can save all your data. I have a file server at home and realy like the RAID 5 setup in that.

Ahh...RAID 5...striping with parity...a God send! Firstly let me just say that RAID on a home PC is only "more trouble than it's worth" to people who don't know what they're doing! To add to what Johns mentioned earlier, you have 4 common RAID setups: - RAID 0-Striping (require at least 2 HDDs and spans the data equally across the drives to give imporoved performance), RAID 1-Mirroring (requires at least 2 HDDs and casts a copy of everything stored on the main drive to the mirror so if there is fault in the main drive the system falls back on the mirror to run), RAID 0/1-Striping with Mirrioring (Requires at least 4 HDDs), RAID 5-'Striping with Parity' (requires at least 3 HDDs. The combined capacity of all the drives will be totalled with two thirds of that being usable, the remaining third for error correction). Some motherboards/RAID cards will give you the option to have a failsafe/hotswap disk that will take over if the entire RAID Array fails. This disk must be equal in size to the size of the Array. I.e. You have RAID 5 configured over 3 30Gb HDDs. That will give you approximately 60Gb usable disk space with the remaining 30Gb being used as parity. If you want to set up a hotswap disk, that disk must be equal to or greater than in size to 60Gb. Hope this helps and isn't to complicated. LOL