I want to build one of my PCs in to a home server to live under the stairs, so it needs to have:

Remote access (I dont want a monitor etc under the stairs!)
data protection (raid array is it called?)

The idea is to be able to put all my music, videos, pictures. I have tens of thousands of files and its getting to the stage I cant remember what PC they are on!!!

So, what software do I need?!

Thanks!