I'm a big fan of this psu, mostly because of the price because I'm a cheap person. http://www.newegg.com/Product/Product.aspx...N82E16817148027
. I've used a couple of them, including one in my own system and it's been running fine for about eight months now.
If you want something thats a bit higher quality and 80+ certified, these antec earthwatts are pretty nice. http://www.newegg.com/Product/Product.aspx...N82E16817371006
. If you can get the mail-in rebate to work, that's a very good deal. 80+ certified means it doesn't waste as much electricity. You'll save a few dollars on your electric bill.
You can just look around for some deals. I'd say anything 350 Watts or higher and make sure the amps on the +12V rail(s) are 30 or more. Read the reviews also, but I would only listen to the ones that say the person actually bought the item.
"I think there is a world market for maybe five computers." - Thomas Watson, Chairman of IBM, 1943