It is not true that there are no socket 478 boards with PCIe. It is true that the only one widely available in the USA uses a "fake' PCIe slot that's actually 4x not 16x (IIRC, an ASRock board). I think Asus and Albatron makes some but those are not available on these shores. One forum member recently bought an Albatron from some Asian shop and paid $40 to ship it here. He actually got it and it's the real deal.
Socket 754 is as dead as socket 939 - both to be supplanted by AM2. No dual channel or dual core? Big whoop! For my purposes now, and for the forseeable future (couple of years) dual core is of no use to me. Yes, I'm typing this on an overclocked x2. No, I notice absolutely NO difference in performance between this and my overclocked P4 without Hyperthreading from two years ago that I still use. I also noticed no difference in performance from the socket 754 A64 that I was using before I got this x2. I DID notice big differences with gaming from upgrading the video card. With PCIe available for socket 754, that makes for a nice budget gamer.
I'm not saying that there is no value to dual core. My point is that not everybody will benefit for the next few years and you do a disservice to others by convincing them to pay more for dual core (or dual core capable) if it is of no benefit to what they are planning to use the computer for. Now, the OP mentioned multitasking - sure that is one benefit of dual core. Is he really going to multitask? Many people who think they are multitasking are really task swapping. Got tons of application windows open and running? Well, which ones are actually taking up real amounts of CPU time? Encoding a video or folding in the background? Sure thing! Having a couple of IM, your email software, bunch of browser windows, couple of documents open... I don't think so.