Well I've only play Fallout 3 but I've heard these are a bit different so I want to be sure.
Fallout 3 really isn't a game in the same series as Fallout 1 and 2. It's more like a spin-off in a different genre. FO1/2 are 2D, isometric CRPGs in the vein of something like Baldur's Gate, so you experience with FO3 won't have any bearing on what you think about FO1/2. The only thing that's remotely similar is the setting.