I feel that this drow thingy is starting to get a bit ridiculous.
Fantasy milieux can be in three flavors:
1. "Strict" high fantasy, where alignment and ideals are almost inherent (LotR, Dragonlance, perhaps the "Old Grey Box" version of FR)
2. Middle-of-the-ground fantasy (today's Forgotten Realms)
3. Low, "grey area" fantasy, almost like real life, where there is no real good or evil (except for those celestials and infernals) and/or a different moral scale is used (Oriental-based worlds, George R. R. Martin's Song of Ice and Fire)
There are others, but these three are the most common ideology for any fantasy world. In "strict" high fantasy, drow are evil to the core and there's no getting around it. In middle-of-the-ground fantasy, drow SHOULD have good outsiders beyond Drizzt and Qilue and her tiny cult. In "grey" fantasy, drow are just elves of a different skin color and magic resistance. Lolth may be lawful good, or a sect of her religion "hijacked" to chaotic evil (or vice versa), but few, with the exception of those who follow or normally fight against such religion, really care whether or not one or the other is right.
For me, (1) is great for a fantasy epic, but utterly stupid for a campaign simply because you are "railroading" with some cardboard cutout. (2) is most optimal for what I like in a fantasy setting that I play, and (3) feels a little too much, perhaps except in those vampire campaigns.
Put your setting in one of these three flavors and from there, tell if so-called "evil" can become good. We are not just limiting ourselves to drow here. Drow are the most common archetypes for this argument simply because of R.A. Salvatore and his cheesy drow ranger, who seems to get far more credit than he deserves.
Back to the subject. Compare the drow to, say, the Muslim Middle East. (No, they aren't evil, 'xept Al-Qaeda and those who support homicide bombers, but bear with me. I apologize if I offend anyone in this topic.) There, if you (a) fail to follow the tenents of Allah, or (b) dare to treat a Jew with respect, you would probably be executed. Strict, huh? The ideology of following faith in this real-world example is just as strict as the Llothians in Menzoberrenan (sp?) (I'm Roman Catholic, but anyway...)
Are there outcasts? Yes. Any of them inherently "good", at least to the U.S.'s POV? Yes (i.e. Turkey and post-Taliban Afghanistan). Are there followers under Saddam and the like kicking down doors, rooting out every single home, and searching if you dare break the two general rules? NO. There are rebels all over the place ready to take out these dictators and post a U.S.-like democracy. Ergo, there are always some kind of deviates in certain situations. As a realist, I think that evil and good exist in EVERY race, real or (logical) fantasy, and telling that so-and-so is good or evil, lawful or chaotic merely points to the status quo. I allow good cambions, evil half-celestials, and MOST DEFINITELY good drow.
For the record, I am writing my novel/game world (somewhere between types 2 and 3) and created dark elves that are mainly good, compassionate, and noble. They think that based on what happened in the past, each of these "shadowed" elves, with cursed grey skin and sensitivity to light, are elves that have to redeem for another dead elf's misdeeds.
Nice twist if you think about it.