You definitely want a Pentium M (Centrino) notebook right now if you want the lighest weight notebook (and thinner) with the best battery life (at least 3.5 - 4 hours using wi-fi or up to 5 hours with wi-fi turned off).
You need to specify which LCD screen size you want. That has a large impact on overall weight and the choice you make. A 15.4" widescreen LCD like I have on my Compaq X1000 series (same as HPZT3000) or the Toshiba M35S456 (on sale for this week for $1749 after rebates with multiformat DVD burner/CD burner and Trubrite LCD) weigh in the 6.2 to 6.5 pound range.
It is advisable to get dedicated video RAM unless you know you will never use it for anything but web surfing and Microsoft office and both of the above have the option to get up to 64mb dedicated video RAM.
Note: you can save up to $200 by ordering a CD-RW/DVD ROM (only plays DVD, doesn't record) instead of a DVD burner/CD burner but you seem to want that.
If you drop down to a 14.1" square LCD you can get to 5.5 pounds or less (and the notebook is less wide).
The Compaq X1000/ZT3000 can be customized online and you can save a bit more money and get exactly what you want.
But if you want a solid prebuilt notebook the Toshiba M35S456 has a 80gb 4200 rpm hard drive, 64mb dedicated video RAM, the Intel 54G wireless built in, the 15.4" LCD with Trubrite, 512mb PC2700 RAM, multiformat DVD burner/CD-RW (some DVD burners are not multiformat -- this one does all formats + / - and DVD RAM), etc.
Again, this $1749 after rebates at Compusa (this specific model is selling out so what they have is what they have -- $1999 regular retail) but if you don't need a DVD burner (only CD-RW burner and DVD ROM for playing DVD's) you can easily get under $1500 and even closer to $1,000 ordering the ZT3000 at Hpshopping ($100 custom order rebate, etc). See X1000forums.com for details on the Compaq or HP or notebookforums.com for information on the Toshiba.
I know littleabout notebooks and everyone I know seems to be telling me different things. What do you think I should get?
I want something that is...
-good battery life
-quiet for the classroom
-ability to burn and use DVD/CD
-wireless internet easy to do