Thoughts:
* DVD/CD-RW - always nice to watch a DVD movie when your out somewhere
* Lots of RAM...easy to upgrade though (once), so not a huge deal on the initial buy as long as there's a slot to expand. 512MB should be fine now, but in 2 years, you'll be wanting 1GB.
* HDD space - 40GB should be fine. HDD's can be upgraded, but it's sometimes a pain on laptops. Most laptop users don't seem to put a ton of videos/MP3's on there.
* Gaming:
---- 64MB...welp, RAM is not an indication of video card performance.
---- Laptops with "embedded" chips such as the Intel Extreme Graphics and S3 and others are pretty sorrowful on the gaming today...let alone in 2 years.
---- I'd be thinking about a minimum graphics chip of an ATI 9600 or nVidia 5600
---- The mobile 9600 isn't quite up to speed of the desktop 9600...likewise the 9700 isn't quite up to 9700 speeds...the 9700 is more like 9600 speeds. Similar story for nVidia chips
* CPU - The 1.7GHz Pentium-M is a nice chip. Gaming-wise, you may be happier with a 3.0 or 3.2 Pentium 4/Athlon 64...but battery life will suffer noticeably.
* 1.7 vs 2.1...yeah, it's a little bit of a boost, and sure, I'd want it. But look back four years...how much different is an 800MHz vs a 1GHz machine in running today's applications...not a ton...but a tiny difference.
* The Alienware stuff is pretty cool....plus in 2-4 years, if you wanted to upgrade...pay the parts, and they'll rip out whatever...video, motherboard, etc...and do the upgrade.
Here's a $1500 laptop from iBuyPower (not sure of their quality/service). For another $50, it configures to a P4 3.2 with a 9700 video card.
I think eMachines (now under Gateway's umbrella) has an Athlon64 3000 w/an ATI 9600 for around $1200 these days.