I know what you mean.... I discovered Buffy at the beginning of season 4, and only knew about Angel and the whole sending him to hell thing because of the "previously on Buffy" tags as well as what they showed and explained on Angel (season one).
I really enjoyed both shows and tried not to miss a single eppy, but when my friend, Barb, saw Buffy on FX, she was hooked instantly. She was begging me for tapes (which I don't keep) and asking me all kinds of questions about the early seasons.
Good thing she's been able to catch up with all the re-runs on FX or I'd be going nuts trying to keep her abreast.
Then, my other freind, Mary, loves David Boreanaz, so she's been watching Angel since day one, but avoided Buffy (because of the whole Buffy sent Angel to hell thing) until this season, when she fell in love with James Marsters. Now she can't get enough of either show.
What am I to do with you addictees?