Mac's are great, they are the highest rated computer in Consumer's Reports, but expect to pay three times as much for them.
For $400 to $500 you should be able to get a good laptop that will get you through a few years. At this price point you will get a decent processor speed, hard drive space and memory, things that are lacking in this price range are sound systems, graphic cards, battery life and the sturdiness of the case itself. This is the range of laptop I have now. I have a 2 year old Toshiba. It still works fairly well, the battery will not hold a charge so I always use it with a cord, and the case has some cracking issues. However, I feel that I have got more than my money out of this machine for the abuse I give it!
If you go up to the $600-$800 range you are going to get a better machine. Usually better speakers, sturdier case, sometimes better battery life, faster processor and more memory. If you can afford it I would get something in this range, but like I said my cheaper Toshiba has worked well for 2 years now under heavy, heavy use.
If you go up even a little more in price you again will get faster processing speeds, more memory and probably very good batttery life. Really, I don't think its worth going past the $800 mark.
Really, the only brand I don't like is Dell. I just personally don't like the styling and feel. Also my bf had a total lemon Sony Viao, so that brand totally turns me off, but I know people who love their Viao's. His current HP is VERY nice and it was in that $600 range. Great graphics, strudy case, good speakers, lots of memory and hard drive space.
So that's my ramble about laptops. I pay a lot of attention to the computers my friends and family have and have formed my opinion from that.
Best Buy has great deals in the month of August, I got mine 2 years ago in august and my BF got his last august. If there were a time of the year to get a great deal on a laptop it is now!