I want to try them. Are they free now? if I can't get both, which one is better?

Fallout 1 & 2 isn't freeware/abandonware. So you'll have to purchase it if you want to play it legally. They are available for purchasable download at:

http://www.GOG.com

http://fallout.gamesplanet.com/game-fallout-trilogy2-interplay.html

That package at Interplay includes the Fallout: Tactics spin-off. It's not like the other two, it's very combat oriented, and has little RPG element, but for a combat/strategy game, it's quite good, in my opinion at least

There are box sets still being sold. The most recent one I believe is the White Label release, but if you can't find a copy in-store then your best bet is an online download. Or a box purchase from Amazon.

As for which of the originals is better. I'd say start with the first one regardless. My personal fave is FO2, but it's a continuation of FO1. So if you like your RPGs to have a good story, I'd say FO1 first You'll also appreciate the subtle engine improvements in FO2 alot more if you play FO1 first.

i recently bought the interplay trilogy.
i expect good things, since, ive had to endure arguments against fallout3 by the fallout1 and 2 crowd.

but, ill say right now: a good story is NOT what makes a good rpg. my character and the control given to me is what makes an rpg. control and options. micro and mass management. development. skills. skill trees. non-linear dialogue. story. choice. options. gameplay elements.
ALL of it: including, fps, action/adventure, and exploration.

Fallout was free for a few weeks on Gametap, but now F1 & F2 require an account.
http://www.gametap.com/video-games/Fallout-20000411-0.html
http://www.gametap.com/video-games/Fallout-2-20000413-0.html
http://www.gametap.com/video-games/Fallout-Tactics-20000014-0.html