The fastest speed on my PC ends within a second, but all the others run at the proper rate of time. That's the one bad concession other than the HLP files being useless.
SC2K WIN vs DOS -- resolution, slightly nicer graphics, windows audio which has that nice midi music for the jingles, just a little more fluid/easier to navigate in windows versus faux windows like menuing in DOS. I suppose it's a bit of preference, but it's also cool being able to play the game without having to fart around with DOS Box.
Oh and Leo, I got C&C and Red Alert working. I actually found the CD that I thought I had thrown out and found this oddball all in one catch all super patch for that specific CD and it worked. It still won't work with Tiberium Sun which sucks, the start menu won't take a mouse click to get into the game, but the others work and maybe the ones post-Tiberium do too but I haven't bothered.