Our Best Buy actually has somewhat competent employees. I know that's not true for all their stores, because I've been to a few with idiots working there. That's not to say the local guys are perfect. Some guy was asking how he could take out a partition and gain the space back off a partitioned drive, and one of the employees said he'd have to format. I stepped in and corrected him, but at least the employee didn't try to sell him a new computer to "fix" that problem (something that a lot of employees at other Best Buys would have done).
Yup. Your mileage will vary...if your local Best Buy has intelligent employees, that's awesome. To sort of rephrase what I had originally said...don't go into Best Buy (or any store, for that matter), without having any clue what you're looking for. Generally speaking, you aren't going to be happy with what you end up with in the long run. Have a basic knowledge of what kind of specs (processor speed, hard drive space, RAM) you're looking for and what they mean. Do you need additional software or peripherals? If you have a budget, make sure to include extra expenses like that in addition of the cost of the machine. Don't let anyone try and push you into a sale - if you're not ready, don't sweat it. A computer is a big purchase, and a lot of money. Impulse purchasing is probably the worst thing you can do to yourself.