Friend of mine from a past job loves Pearl Jam. He has almost everything they've ever done. Not just the studio stuff, but the live, the covers, everything. Something like 700 recordings. It's a sickness really, but it makes him happy. I asked him once for recommendations and he gave me a list of like 60 songs. Too many choices. They're a great band, no question. Their two best albums are "Ten" (1991) and "Pearl Jam" (2006).
"Vitalogy" (1994) and "Binaural" (2000) are also very good. They've really never done a "bad" album, but those are best four, IMHO.
Out of curiosity, do you listen to any Red Hot Chili Pappers? Most people who like Pearl Jam also like the Chili Peppers.
Also, if you're downloading songs, check out a tune by Incubus called "Anna Molly" (it's pronounced "anomaly"). Very good (and very catchy) song.