Another vote for the
MacBook. I've had mine for about 7 months now (got it shortly after this new model was released), and it's been just a fantastic machine. Lightweight, very fast, very reliable, and a great battery life. (I routinely see 3 to 3.5 hours; if I dim the screen and am not using the WiFi, it'll go over 4.) Though originally equipped with a Core Duo, the new models are now using the Core 2 Duo processor, which I understand runs cooler and uses even less power.
They start at $1099. With your budget, I'd go for the mid-range model, which as a slightly faster processor, more memory (1GB), bigger hard drive, and a dual-layer DVD burner. The 512MB in the base model isn't really adequate, but the 1GB that's standard in the mid-range model is enough for comfortable usage. If you want to go all-out, you can either get it custom-configured with 2GB for $175 more, or you can add it later. Since your budget is $1500, I'd go ahead and get the 2GB now -- the Mac operating system is very good at using whatever memory is available for caching and such to make the system run faster, so it'll be well worth it.
And if you want to upgrade the memory and hard drive later, it's very easy: pop out the battery, unscrew a little cover, and it's all right there. Two levers to pop out the two PC5300 memory modules, and the SATA hard drive slides out just by pulling on a tab attached to the sled. (I just replaced my original 60GB drive with a 120GB drive, and it took about five minutes. I did it so I'd have room for videos on the road without taking the discs. I use a program called
Handbrake to rip DVDs to the hard drive; it's great.)
Even the power connector is unique: It's held magnetically, so if you manage to trip over the power cord (or a pax does it in a terminal when you have the cord stretched out), it breaks cleanly away with no damage to the computer or the cord, and without pulling the computer off the desk. Very, very slick.
It comes with a ton of software, including video editing, a slick photo program, DVD authoring, and more. It will run Microsoft Office if you need it (Word and Excel have actually been around longer for the Mac than they have for Windows), or you might try the free
NeoOffice, an enhanced-for-Mac version of
OpenOffice.org, which can read and write most Word, Excel, and Powerpoint files. If you have a retail Windows XP install disc, you can even install that if you like, and use it to boot the machine. Or you can use
Parallels, which will let you run almost any OS at the same time without rebooting. I use it with a Windows 2000 CD I've had for years, and just put it on my external monitor. I can just roll the mouse pointer from screen to screen; it's seamless.
Overall, a fantastic on-the-road machine; I highly recommend it.