First off, glad to see you are still coming here to CF!
Okay, now down to business. You've got a tight budget of $600, and all of the systems I found stretch that out to the last few buckaroos. Here they are in order of best (1)->worst (3):
If I was the one having to choose a laptop for $600, there's no doubt in my mind it'd be the HP. No doubt. I don't like Dell, and if I had to get one, I wouldn't get an Inspiron; unfortunately that's about all that I could get into your budget. And the Lenovo is built well, but spec wise, it's going to get it's rear kicked by the HP.
You are getting the best for your money with the HP IMHO.
Anyone else can certainly bomb over here and add some suggestions. I'd be surprised if 01001010 doesn't show up and help out...He'll point out anything I missed.