Minimum specs these days are something that's about 1 - 2ghz and dual core. It may or may not have a dedicated graphics processor and retailers will still use IntelGMA. 1-2gb of ram, DDR2, is probably the norm now as well. At least a 150gb hard drive.
If you want to get a good gauge on minimum spec systems definitely check out the netbooks. They're cheap, reliable, and meet everything + more that you could expect from a budget laptop. They start at around $300 and go up from there. The only drawback is the small screen but that really isn't a big issue.
http://www.newegg.com/Product/Produc...82E16834230116
Newegg is out of stock but you might be able to find it somewhere else. I have one from about two generations ago and it's amazing. Also very good battery life.