I will be in the market for a new MTB this year. My current ride is a 2004 GF Wahoo that I bought new 6 years or so ago. The bike has treated me very well, but this year I started to get into singletrack and found the Wahoo to be a little lacking. To begin with, it is very heavy and takes a lot of power to get going. Also, I can't quite put my finger on it but it just doesn't "feel right" when taking sharp corners bombing drops and hammering up through mud. The components are also starting to go. It was a nice all-around bike, but I feel like I have outgrown it and that it is time for an upgrade. To be honest, I knew next to nothing about bikes when I first got the GF and don't know much more about MTBs now. Basically, I am looking for a lightweight ride with mid level components that can handle moderatly agressive singletrack. I don't want to spend much more than $1000.00. I don't think I need a full suspension, but I am not sure whether to look at 29ers or not. Defininately want disk brakes.

There are a ton of bikes in this price/performance range, and I was hoping for some recommendations as to the best "bang-for-the buck" at this level to help narrow the field.

Thanks.

29ers are cool if you want to go fast and roll over bigger obstacles without having to bunnyhop, but they don't make much sense unless you're pretty tall. I've heard the reason is that the wheelbase is longer on a 29er, so steering isn't as quick and nimble as it would be on a 26er. Also, the bigger wheels will flex a bit more and may be heavier too. How much of a difference this makes for a recreational rider is hard to say, but I'd at least test ride one if you can. As far as full suspension goes, I'd skip it. At the price point you're looking at, you're not going to find anything that great (not new anyway).
FWIW, I have a Specialized and I really like my bike. I think the Specialized Rockhopper SL Expert looks pretty cool for a good recreational hardtail. The MSRP is a little more than you were saying you wanted to spend though.