Start with The Dark Side of The Moon, probably the best album ever recorded, Sgt. Pepper and Pet Sounds nonwithstanding.
From there, you may jump forward to the Wall, but I would suggest you jump backwards instead to Meddle. And although many overlook Animals, it has some of my favorite work (as does the Delicate Sound of Thunder).
Yes, they WERE that good. See if you can get a box set for cheap, or borrown someone's Wish You Were Here, DOOTM, and The Wall, download them to your iPod and play them for a while, in their original order, no shuffling.
If you feel the need to know some current music, The White Stripes are releasing an album of songs tomorrow (6/19) that is supposed to be quite excellent.
"Here You Leave the World of California Today and Enter the World of, um, er, California Today."
I saw their tours from "Meddle" (in Westchester New York) through The Wall.
What was most impressive, beyond the stage show (remember the lasers bouncing off the pig? The giant rotating sunflower made out of mirrors?) was the sound--Pink Floyd always used a quadrophonic sound system, and the audio was simply unbelievable. I understand that David Gilmour does some of his own mixing on stage now, and am sure that sonically it's still a marvel to hear.