"'Reign in Blood' was a vicious and sinister masterpiece of furious speed and violence that may never be topped. Its ferocious ten songs in 28 minutes still reigns at the pinnacle of thrash metal almost 20 years after it was released."
Quite a good guide I must say, though I disagree about Possessed, I have 2 of their albums and they were awful, I might go find them again and see if ive changed my mind... I havent heard any Bathory either, I think I ordered one of their cds in an amazon shipment I have coming, but I cant remember... I still have never heard Celtic Frost either, do they have a Best Of?
Yep, I agree. Possessed were actually pretty bad! But 'Seven Churches' is still regarded as the first real death metal album. Their guitarist is now in Primus actually, and their second album was produced by Joe Satriani! If you're going to get a Bathory album, I'd go for "Hammerheart" personally. As for Celtic Frost, they have a 'best of' CD called "Parched With Thirst Am I and Dying".
Check out Hellhammer too, they are the same band really, just before Celtic Frost were formed they were called Hellhammer. It's a bit more raw and angry.
"Parched With Thirst Am I and Dying" is sort of a best of, but more of a compilation for the fans, has some non-album tracks on it and stuff, as well as some classics. It has some awesome stuff on it, but I am not sure if it would be the best place to start with the band.