Bit-Tech has a good series on building your own Ubuntu Linux server. Written by Ken Gypen, It's a clear guide. (I sure wish I could write that well!) They're at part 2 of at least 3. This is well worth your looking at.
Yes, I know a lot of you have had your imaginations captured by Windows Home Server. To a certain extent, so am I. It's certainly the most desireable product from MS in quite a while and I find it exciting, too. Even so; a Windows server is not everyone's cup of tea, for a variety of reasons. And then there is the fact that a lot of us would simply rather do it ourselves, whether to learn, out of concern for some aspect of performance or to save money, perhaps by utilizing some of that less than current hardware in the closet. Should you fall anywhere in there, this series of articles is for you.