Just going from the brands we sell at my store and the problems I've seen them have:
Toshiba A200/P200 ... Toshiba has seemingly taken care of the motherboard problems they have been having the last 2 quarters. We were getting tons of units back, but have had very few back lately. They have a nice, solid chassis and I've yet to see a cracked/broken LCD on one. They have a GPU compartment and connections in most models I've opened up, which leaves room for upgrade if you get one w/ an integrated graphics processor, although laptop GPUs are very pricey. Unfortunately, the hard drives are still not physically attached to chassis and a solid bump can knock it out of the SATA connection. Also, the "universal" keyboard design pisses me off; the left shift is too short and the enter key is oddly-shaped. Overall, Toshiba would probably be my choice lately as far as performance and quality per dollar goes.
Hewlett-Packard dv2000/dv6000/dv9000 ... HP's laptops have been the most problematic of any of the brands we sell for the last quarter. I don't know what changed from earlier in the year because they were quite a bit better, but now, I hesitate to recommend them because of the problems in addition to HP's terrible customer service.
Acer ... Acer generally offers up good hardware performance for the dollar; however, they pair it with shitty, custom-made, performance-leeching software. Acer released a new chassis design which is a lot more solid-feeling than their previous chassis, which was quite flimsy and poorly-built. While it certainly isn't better than Toshiba's, it is on par w/ HP's. Acer has generally been one of the more problematic brands we sell and not much has changed in that regard, except less chassis-related incidents (cracked LCD screens, broken hinges, etc.). Fortunately, unlike HP, Acer actually has good customer service and gets shit fixed quickly.
Sony ... I don't see too many Sony's back and, when I do, it's usually something common (i.e. battery). They cost a bundle, but always seem decently built. Sony has the worst customer service in the universe by far, so if you do run into problems, you're better off slitting your wrists than phoning Sony for help.
Apple ... We only sell the Macbooks, so this is based on them and not the Macbook Pros, which I'm much more fond of. Let's face it, the primary deciding factor here will be how much you hate Windows Vista (or, to a lesser degree, how much you love Apple). I personally like Vista, so the Macbook doesn't present a strong case to me being that it's $1250 for a model that lacks some pretty basic features such as a DVD burner, a decently-sized hard drive, and a decent amount of USB ports, all features which are present on even $500 Windows-based laptops these days (though $500 Windows-based PCs obviously don't perform anywhere near as well, just pointing out features here). The saving grace of the Macbook is the Intel Core 2 Duo T7000-series CPUs which provide snappy performance. IMO, they should've upgraded the memory to 2 GB when they released Leopard as it's not quite as fast as Tiger is w/ 1 GB, however RAM is dirt cheap these days, so as long as you don't pay Apple's outrageous upgrade prices, it's not a big deal. For whatever reason, I get people in with keys falling off on the Macbooks at least once a month (I've only ever had 2 other laptops have this issue: 1 HP and 1 Acer). However, overall, the Macbooks are fairly problem-free, though the cost of repair is huge. Apple's service is decent, certainly better than average, but not nearly as good as Acer's, in my experience.
If you're getting Windows Vista, make sure you get AT LEAST 2 GB of RAM and I would advise a Core 2 Duo CPU (preferably a T7000-series) as they perform the best by a significant margin. If you find a laptop w/ a good CPU, but it's lacking in RAM, don't worry, RAM is easy and cheap to upgrade. You can pick up 4 GB of RAM for under $100 off Newegg.