The critical thing is that you buy a notebook with dedicated video (ATI or Nvidia). The games you mention might be ok at 32mb dedicated graphics but you can get 64mb for only a bit more ($50 more for HPZT3000/Compaq X1000 -see X1000forums.com) so get at least 64mb if you can.
Doom 3 will only run at reduced settings even with 64mb dedicated. So, if you are going to be playing more games in the future look for an notebook with the ATI 9600 or 9700 video card with 128mb dedicated graphics (Acer 2025, Acer Ferrari, Dell 8600, etc).
Note that HPshopping has a $100 instant rebate and $100 custom order rebate right now if you order it custom (you can order less RAM and add more later yourself and save $ and get more RAM)
Also, the Toshiba M35S456 with Trubrite is outstanding but it has a DVD burner so it is onsale this week at Compusa For $1799 after rebates.
All the notebooks I mentioned are Pentium M centrino based and will get you 3.5-4 hours using wi-fi or more battery life not using wi-fi (similar life for DVD's)--intense game playing will be somewhat lower but still much better than a Pentium 4M hot running notebook.
Whatever you do, do not order a notebook with integrated (shared) video memory unless you will only be playing Solataire.
I currently have a duron 1.3ghz, GeForce 5900 Se, 80 gig hd and I was wondering What would be a good notebook that would be faster then my desktop and reliable. The only games I play are command and conquer generals, diablo 2 and knights of the old republic, command and conquer renegade not high graphics games like Doom III or Far Cry. I've looked at the gateyway notebooks at best buy and they seem pretty good. My price range is about 1200-1600.