Well best idea is go to a store Like walmart or k Mart something the sell everything. And look at the software. Yes some software they have it dual OS windows/Mac. Really it depends what you are going to do with the laptop.
What you are going to have to do is start asking your self all of this.
How much battery life do I want. Check centreno, Intel And Amd Moble and Apple Laptops. Then check the reviews of all of them.
How fast you want it? Speed well This is where it might be tricky. For you might have to use Desktop reviews. For I notice Toms site and others only do test on Amd and Intel Not Apple. A good place is PC mag. They do test on all three and on laptops.
Http://www.pcmag.com
Then there Size. And how you want it to look. Well there 60 differnt types of laptop companys. From 6Lb to 11Lbs Mine about 10.5lb. But It dont feel heavy to me.
Then What do you want in the laptop. As you can see with me It a intel p4 3.4ee 1 meg of Ram. Two interal 80 gig hard drives and 256 meg ATI MOBILITY™ RADEON™ 9700 8X. 17in Wsxga. If Amd had a two bay hard drive laptop I would of look there.
Then there Ram. Right now there 172 Pin chips And 200 Pin chips for Laptops. A note on this if you have 1gb of ram. Make sure it one 1gb of ram chip. Not 2 512 Meg chips. So later when you want to buy Ram you just have to buy new chip 1gb ram chip. Not discard two 512 chips
Screen size and type of screen. It another part you want to look at. Size and type of screen Right now on 15in. xga, sxga, xga, wxga, sxga, uxga, qxga, Wsxga. The pick size is differnt on each. Like xga has 89per inch And wsxga like 140 per inch. It depends on the company that make the monitors.
Then there battery life. And types of batterys Like Mine on Reg 8 cell batterys with subwoofer or tvcard. would only last 1.5 Hours. But It supported 12 cell batterys Which last around 3 hours. But they take a little more space. So I could not get the subwoofer or tvcard. Which I might later to get the 8 cell and TV card. To watch tv on my 21inch Monitor.
A good place to get info on PC and Laptops is http://upgradingandrepairingpcs.com/
The Book upgrading and repairing Laptops. Is good detail. But Mostly on Amd and Intel. Nothing on Macs.