It ain't so!!!
First, I've gotten Far Cry to run quite well on my Dell 8600 (1.7GHz, ATI 9600 128 MB, 1 GB RAM) with the game settings as follow: 1024x768, Very High graphics, No AA. Of course, I don't see all of the super, hi-end graphics the game offers, but no one could expect that. Get a maxxed-out desktop if you wanna see the best graphics possible for FC or any game.
Second, a new notebook purchased today will NOT be useless for future games like Doom 3 and HL2. Notebooks won't be running those games on the highest settings...most desktops won't even be able to do so...but an 8790, GX7, m:860, AX7, etc. will run the best games at reduced settings, and the games WILL look quite good.