Upload & Sell: On
The original Windows Home Server (based on Server 2003) is a near perfect solution for the typical home user who needs something that works out of the box, and is not interested in fiddling with the OS to do much more than backup and sharing data. It backs up up to 10 Windows PCs and offers drive pooling where the user can assign redundancy to selected folders (multiple copies on separate drives to protect against hardware failure). I haven't used the new WHS11 yet, but I've heard good things about it, but it doesn't natively provide drive pooling.
If you are a bit more tech savvy and don't mind doing your homework, there are better options out there. FreeNAS is a user friendly server OS that allows you to use the Oracle ZFS file system. ZFS essentially allows you to move away from expensive hardware based raid solutions to an incredibly powerful and flexible software based raid system that is miles above anything else available on the market today. And its free. If you know Unix, you can also use ZFS on a data server running BSD or OpenSolaris/OpenIndiana to exploit everything ZFS has to offer, but this is NOT recommended (or needed) for the casual user.
Whatever solution you choose, make sure you educate yourself on the protocols you will need to use to recover data in the event of drive failures. This is critical! As your server grows, so does your risk. For critical data, you also need to plan on redundancy where you store backups offsite, either using an online backup service, or on external hard drives that you rotate on a periodic basis. Invest some time in planning to figure out your immediate and future needs, and this will make the upgrade path easier and less expensive.
In my home I'm running a WHS box with about 24TB of unformatted storage. This is a my primary data server. I'm also running OpenSolaris as a VM on a separate ESXi box as a second data server to keep a second backup of all my critical work stuff. Over time I plan to migrate all my data storage to a ZFS based system.