It started for me as a kid playing Half-Life (around 1999), and then installing (but never playing) and running around empty maps in TFC going "Man, I wish I wasn't on dial up so that I could play this." Played CS beta in my schools computer lab. Bought the Orange Box for HL2, as at the time I finally had a computer that would run it, installed TF2 and did the same thing I did with TFC due to still having a shit connection. Got around to playing CS: Source with a few work buddies on off hours, and then tested the TF2 waters. Finally got myself a decent, non-dial-up connection around the start of Mann Vs Machine, and have been playing steady ever since.
I still have the original pirate burned CD's and keys from the days when Sierra games was still a big name (not an old name resurrected), of Half-Life Game of the Year, Opposing Force, and Blue-Shift.