you sit all night at your computer

And now, an experiment in crossposting, mostly so I have everything gathered in one place for this.
So... the time has come to replace Hex. It's still a reliable little machine in its way, but it's nearly eight years old and can't keep up with the Tubes properly anymore. Pottermore was one thing - I was expecting to have some trouble with all that Flash - but I can't load a page with a lot of .gifs or Youtube embeds and expect to see the whole thing in a timely fashion, if at all. The final straw was having to crash my browser rather than work on a Google Doc with two sentences in it the other night. I want to look into possibly getting some freelance things, and I can't do that if I can't work on anything.
So once my tax refund's in, I'll be shopping around (not getting rid of Hex just yet, but it's time for a new primary). Since I get a discount at work and it's rather cheaper overall, I'll be going PC for the first time in my life, aside from this being the first time I go computer shopping for myself; Hex was a high school graduation present.

Do you guys have any recommendations for which brands have worked well for you? My only requirement is that it be a laptop. I've heard good things about Sony and Toshiba and iffy things about Dell, HP and Acer; I'm expecting my budget for this to be around $500, not including sales tax, though it could be a bit more.