Memories...
Started out with the 'red box' basic set, and modules B1-4 - all for christmas. Shortly thereafter picked up the Expert set for myself.
I was really hurting for character sheets, but all the store had was the old orange AD&D NPC sheets - two to an 8 1/2 X 11 page, if anyone remembers. After staring in mystification at all the tons of extra spots to write things in (THACO? What's that?), I went out and bought myself the 1e AD&D PHB, DMG, and the World of Greyhawk boxed set... and switched immediately to AD&D.
Out of a sense of completeness, I subsequently picked up the Companions, Master, and Immortals box sets, but my heart was with AD&D from that first set of NPC sheets. To this day I still buy old modules or expansion sets that I find used at gaming stores so that eventually I may have pretty much everything ever released for 1e AD&D.