I know the question in the title is a bit broad.
I'm a little confused about NAS storage. I have a Macbook Pro, and I want to set up a NAS Raid box that will be attached via ethernet to my router. I want to then use Time Machine as the backup software for the Mac. Will any NAS do this as long as it has drivers for a Mac? The main thing is I don't want to have to plug in the laptop for the backup-I want it done wirelessly, and I don't want to spend $500 for the 2 Gig Time Capsule. I want something like a 2-4 gig RAID 1 setup.
When you connect over a network, device drivers are not involved since the device is not directly attached to a local bus. Instead you will use your NIC (wired or wireless) to connect to the NAS via a network protocol and using a file protocol (either SMB or AFP most likely)(. You will use Apple + K (or Go -> Connect to:) in Finder to connect, and from there mount the network share. There is no reason you can't connected to a wired device through your wireless router/gateway.
You then need to research how to create a sparseimage for time machine backups on a network share. Check out lifehacker.com there are a few archived how tos on how to do this. If you can shell out, I think some of the Iomega IX2 and IX4 devices have built-in scripts and tools to make this easier, and the boxes are capable of being more than just a NAS, FTP, Torrent, UPnP server, etc.