I haven't played much with C2Ds, David, so I can't say I've experienced the same, but anyone who thinks that benchmarking DVD rips is the way to figure out which CPU to buy has rocks in his head. Clean the crap out of the startup, make sire the drivers are correct, then zip around the UI for a while. If it feels fast, it is fast. All to do with ability to task-switch and access memory, I have always believed.
This is why I always laughed at people who claimed that the P4 was a "good fast chip". Any Athlon XP, even a lowly Sempron/Duron, would blow its socks of on the desktop - which is where it actually matters.
Any task that takes more than a second or at most 5 seconds doesn't matter: you are not going to sit there waiting for it, you'll look away, glance at the newspaper, start another task, post on Storage Forum, something, anything rather than stare at a computer, waiting, waiting, waiting.
And it's not the 5-second tasks that kill you (such as the intermoinable wait for Photoshop to do anything, it's the 1 second and 1 1/2 second waits that get you, as there are so many of them.
Executive summary: if it feels fast, it is fast. Go with the one you like the look of.