There's a handful of good restaurants in the area. I just graduated VT last weekend, so I was there for a few years.
Salem/Catawba, off of rt. 311 about 20 miles north on 81 (about 30 mins from christiansburg), has a place called The Homeplace. It's an old farm house in the middle of nowhere, but is a staple restaurant to the area. It's all country cooking, and as soon as you sit down they have fried chicken, roast beef, potatoes and vegetables coming out on the table. It's not fancy, but is just darn good country cooking. They'll bring out refills as long as you can eat. The house is set right in the mountains also, and the scenery is beautiful. It's an excellent restaurant, and I recommend it to anyone visiting the area.
In Christiansburg itself, there's a few good ones also. Kabuki's is a Japanese Steakhouse style restaurant and is decent. The Farmhouse is the local traditional steakhouse, which also gets good reviews in the area. I haven't eaten in either of these, but they always get favorable reviews as some of the nicer christiansburg places.
If you go 10 minutes west, you'll run into Blacksburg and the VT campus. The few blocks of downtown there are full of restaurants. They're all inexpensive (college kids budget, ha), but quite tasty. Mike's has excellent burgers, Boudreaux's has fun Cajun cuisine, Southern Oven is country cuisine. The happy hours have really cheap drinks also, but during the summer the atmosphere maybe a little more tame since us students are out of classes.
Then, about 10 miles south is Radford. There is an excellent Italian restaurant there called Sal's. I had my graduation dinner there because I liked it a lot, and I have yet to try a dish I didnt like there. Their deep dish and white pizzas are awesome and my favorites. The italian dishes are really tasty as well, and they spice them up to have a nice kick to them.
And there's my first post, lol, a novel on the new river valley. I'm going to miss the area now that I've finished school.