Hard drive choices for home server

I'm doing a new build for my main PC and going to use the old system to build a home media server.

I need to add capacity. The root drive is a 250 GB WD, with a second drive 1TB WD green (I think). I'm going to expand this to probably 4 TB. 1TB for family file storage and 3 TB for media storage.

Should I have any concern with mixing and matching drives (i.e., different manufacturers)? I saw some recommendations for the Spinpoint 1TB drives (for other uses) and was wondering if it would matter much. Since this is going to be a networked device, I don't see performance as a big issue (am I wrong), seems like the network is the bottleneck.

I have not decided if I want to use RAID for setting up the drives. I do plan to back up all my media on to hard drives. Kind of like the idea of filling a media drive and imaging it over to another drive, pulling the image and keeping it in a safe location.