My suggestion is yes, get the Apple TV as I think AirPlay will become a huge part of Apple's living room strategy going forward.
I've found a somewhat convoluted yet surprisingly effective way of streaming videos to my Apple TV from my computer, as long as you have an iPhone, iPad, or iPod Touch. Get yourself the fantastic $2.99 Air Video app. This app, coupled with a free client app you install on your Mac, streams movies from your Mac to any iOS device. You tell the client app which folders to share, and from your iOS device, you see those folders and all of the videos contained within them.
Now, and here's the best part. It does live transcoding to your iOS devices. It supports all sorts of file types: avi, mkv, xvid, you name it. This transcoding works incredibly well, and I've never noticed any sort of stutter or any problems when viewing videos from a 2009 MacBook Pro. So no manual transcoding, or setting up some VLC transcoding functionality.
The even better part is that now, Air Video supports AirPlay. So, you can beam videos from your computer, to your iOS device, to your TV, all while being transcoded live and being controlled from your iOS device. This setup works great, with again, virtually no lag or stutter over a standard 802.11n network.
One caveat, I'm sure there's some sort of quality loss, and I haven't done any detailed comparison or anything to see what that loss is. Everything looks pretty good to my eyes, though my 40" TV is smaller than a projector. But give it a try, as again, it makes watching videos from your computer to TV incredibly fast and simple.