A big part of this answer is: How tech-savvy are you? The more savvy you are, the more you can do for yourself, meaning the less you have to pay.
I like Dells. In the past couple of years, I've owned/ordered about a dozen of them.
Here's why:
1) Great support site. I'm a computer tech, so I'm prepared to do 99% of all repairs myself. Their site has detailed service manuals, drivers, bios updates, etc.
2) Relatively cheap. I spent about $500 on a D600 about 8 months ago, and it's great. DVD ROM, 700Mhz proc, 384 MB RAM, etc.
3) Great support site. I always do lots of research when I make a big purchase like this. They have community forums where people post all kinds of problems. And they have REAL technicians that monitor those forums, and provide useful answers.
Unfortunately, the D600 line has a problem with their touchpads not working very well. I had to have mine replaced, and it still sucks.
Don't buy off of eBay. You'll probably save $50-100, but it's a huge gamble. I bought my laptop from a reputable seller, and he committed fraud a couple of times when I tried to get him to honor the 90-day warranty.
If you can, go for XP Pro. Try to get them to include the CD (instead of just having Windows already installed)
If I were you, I'd save money by getting a smaller HD. Laptop HD's are way more expensive than desktop HD's. I am currently using an old 160GB drive in a USB enclosure for all of my file storage stuff. I don't require it for day-to-day usage (surfing the net, gaming, etc), but it's great to break out when I want to spin some music, video, etc.
You can also opt for less memory; I almost guarantee you that you'll pay MORE for memory from the manufacturer than you would from newegg.com. It requires some tech knowledge to get it in there, but only a little bit.
Go for internal wireless (802.11g). One less thing to worry about.
Definately go to a few different stores, and play with the models they have on display. It's like buying a car--there's no one right answer, since different people like different things. Familiarize yourself with a bunch of different computers, so you can see what you like and don't like.
Spider