Hard drive for Oppo 105 and Sonos

I'm thinking of doing Sonos or something like it and want to start the process by ripping all my CDs to an external drive (that'll give me a chance to decide on Sonos or other similar system while getting the rips done). I want the drive to be compatible with both my 105 and Sonos so when I want I could use the USB connection direct to the Oppo 105 and also have the drive on all the time so it could be accessed by Sonos (if this is possible). What drive would make the most sense for my needs?
Buffalo drives have been mentioned. What do you think of them?

Also, was thinking of two identical drives so I could back the primary drive up. How would you do it?

Finally, looking to spend less than more $$. That is kind of the lure of this, seems kind of inexpensive. Don't want to spend thousands. Though with a controller, HDD, a couple speakers and Connect, not really so cheap. Maybe I'm fooling myself.
If your Oppo has usb 3 capability, I would get one of the Western Digital usb 3 drives. You can get a 2 TB for around 150 and the drive is the size of a deck of cards. I use a 1TB usb 3 drive in my system. You can rip all your music to flac and have room for probably 100,000 songs. The quality is excellent.
I believe that the Sonos needs to pull files from a file server, of sorts, that is on your network. It won't pull files off of a USB hard drive. I don't think it will, anyway.

I believe that the oppo will also play content from over your network.

Using an external USB hard drive is something that many do, but I found it rather inconvenient. Every time you want to add something to it, you have to unplug it and plug it into your computer.

I'd propose one of two things. If you have a router with a USB port, plug the USB drive into that. The better way of doing it would be to get yourself a Synology NAS. They do make a single drive model that is under $200. Throw a hard drive into it and you'll have a drive that you can assess from your Oppo or Sonos via your network and you can access the drive from your computer.

I have my rig setup so that dbPoweramp rips directly to my Synology NAS. I don't even have to think about it. Once the files are on the Synology, I just update the databases on my Touch and Sonos.
Tonyangel is right (sort of). Sonos can only play files that are on the network. Files can reside on any computer folder as long as the folder is being shared on the network. Therefore, a USB hard drive will also work so long as it is visible on the network. The drawback to this approach versus using a NAS is that the PC tue USB hard drive is attached must be on all the time. Using a NAS also gives you automated backup. I am paranoid so I use a NAS configured to Raid 5 then use another NAS set up to backup my primary NAS once a week. I am also thinking about paying for cloud storage as well. Overboard I know but it has taken me 25 years to amass my music collection. I don't want to lose it all.
I was assuming that the point was not to have to leave a computer on all of the time to play music. Otherwise, you can just create a shared folder and put your music into it. Now that I think about it, that's how I started.
Oh, if you are fairly computer savvy, you might also want to try to locate a used Squeezebox Touch. I know that most are taking advantage of the fact that they are no longer made, but I have seen a couple of deals here on Agon that weren't too bad.

The downside to the Touch is that it takes a bit more setting up to get it running and pulling files off of a server. The upside is that it will play files directly from a USB drive and it is IR remote capable.

I like the remote capability, mostly because I use a Harmony 900 with RF. I can quickly move through my play list without pulling out a remote device, like an iPad or iPod, and can control the volume too.
Thanks for all the comments so far. -I do not want to leave my computer powered on all the time. I'd rather just have an HD or NAS that can do the duty. And I want to make sure that my music is backed up. For me, I won't even start the project if back up isn't simple and fairly cheap. I don't want to waste my time with the possibility of loosing some or all of my work ripping thousands of files.

As you are probably aware, I'm not savy at all with computer audio. I like the Sonos product because it appears to be quite easy to set up and maintain with good wireless range. I'd like a way to do this cheaper, but I'm afraid it'll take a bunch of time that I don't have to give and that the end result won't have the ease of use that my wife will require. But, I am still open to any and all advice. Bring it on.
Pokey77,I would suggest Sonos + NAS. As you mention the Sonos is very easy to set up, the interface is fantastic, and its reliable. I was one of the first ones to purchase it back in 2003 I think. No issues. The NAS will allow you to not need a computer on all the time and provide automatic backup. Not the cheapest but definitely easy and robust.
Pardon the expression, but the Sonos is truly idiot proof. It is far easier to setup and maintain than anything else I've seen in the price range.

I have a little single drive NAS and I have it set to back up to two separate drives. One is just a little USB drive that is plugged into the NAS and the other is on a desktop.

Tboooe's solution is more bulletproof, but it isn't cheap.

Whatever you do, don't cheap out on the ripping software. I know that there is stuff out there that works well and is free, but I don't think I've found anything as refined and easy to use as something like dbPoweramp. Save yourself some headaches and spend the $30.