I've played and finished the main quest of Fallout 3 and greatly enjoyed it. Would you recommend the previous games in the series for someone who's only played FO3? I understand the previous games use an isometric camera-view and turn-based combat. Are the experiences of those games and FO3 similar in any way, enough that they would be as enjoyable, or are they so different that you can't really compare them with FO3 and it would be hard to know if someone in my position should play them?

Well, GameTap.com has Fallout on there for free and it's only about ~400MB so if anything you can download it and try it out. The gameplay in FO and FO2 are very similar so if you like the first you'll assuredly enjoy the second. Other than that, I would highly recommend the games to anyone, especially if you enjoyed Fallout 3. Definitely not the same but different isn't always bad.

I'm definitely thinking about trying them out. I still have an older Win98 computer with DOS and it's perfect for older games like Myth, Starcraft etc so I'm looking forward to trying these two out.

I actually just got FO1 and 2 recently. I had played them both a little before FO3 came out but just played FO1 for a couple of hours today. If you can handle the outdated graphics and get used to the way the game plays, it's really fantastic. I like it a lot. I know FO2 is almost the same as I've played that for like 2-3 hours before. I actually recommend playing them if you have the means.

Also if you have any trouble use google or go to no mutants allowed. They have all of the problems I've encountered w/ running the game and how to fix them. (the big one I had was no sound effects, music but no sounds, had to turn off the hardware acceleration on my sound card)

Fallout 2 is the best game i have ever played. ever.

For me its one of the best.
Here is link to similar thread, I did post there links to some good mods/patches out there for Fallout 2:
http://www.gamesas.com/bgsforums/index.php?showtopic=898345

Make sure you patch FO2 before you start playing.

I would recommend FO1 and 2 for everyone who loves RPGs like Planescape, Baldurs Gate series, Arcanum and such.
I mean the real die hard RPG ones.
FO3 is different, fact. But don't misunderstand me here.
It is a great FPS RPG and gets the setting very close to the old style (congratulations to the art department, i just love the art deco), I love it for what it is and that it relives the Fallout spirit but by heart it is an action RPG.
FO1+2 have different combat, Turn Based and so the action sequences can take longer, and with larger groups you have to take your time.
It is similar but not equal to what V.A.T.S. simulates.
If you like "fast" action or only know hack & slay action rpgs like sacred or diablo, Fallout classics is not.

I also have to admit that I have a vivid imagination when it comes to graphics so the isometric and pixelated graphic style of the old games doesn't bother me at all.
For me, the classic Fallout games feel more like reading a good book with various endings and multiple choices which really change the outcome of the game and the overall ending. Something I have never seen implemented so well in any game I played before.

FO2 is still residing on my classics Hard Drive and I once in a while pick it out to mod the cities further to my taste with the damn unforgiving editor ^^ or just take a stroll across the wastes.

Ps.: Oh and yeah, do not forget to patch the games beforehand. I can recommend this patch http://www.nma-fallout.com/forum/viewtopic.php?t=42776