That's funny because I remember reading about in 2000 and 2001 the great graphics coming to pc's "soon". Then I saw Halo 1's graphics and it was like "they're here now!".
The death knell for pc gaming imo, was when consoles went HD. It became way too much hassle to keep the upgrade cycle going when the graphics of these machines -while not as good as promised so far- still look GREAT.
And oh ya, using Xbox live is just too easy. Oh the nightmares of PC gaming online.
To be fair, I'm sure online pc gaming has improved, but I just don't really care anymore.