OpenGL newbie seeks help!

Hey /prog/, I'm writing a cross-platform OpenGL application which does some off-screen rendering. I've found two ways of doing that - with pbuffers and with FBOs, the latter is preferable. I want old videocards to be supported too.
Now tell me, which technique should I use? Do the older videocards support FBO? Do they support pbuffers?
Thanks.

>>14
You're stuck in the past.
You have to agree, the past was much nicer and newbie friendly.

double-buffered window initialisation procedure with mode-setting and OpenGL context creation. It's totally the same thing!
What if I just want to put some pixels on screen and dont care about windows/double-buffering/modesetting/context and other bloated crap?