I first played it 2000-01 when it ran off Half Life as a separate add on pack or something like that.
Since when have you played it and did you have you have any big gaps in between?
I picked up Counter Strike Global Offense but it's not the same, maybe I am growing out of them. It was cheap as chips though. The thing I find with PC games and online console is that now after you buy it you cannot onsell it to someone else, there are some that do but I think it's against the rules.