I see there's a big difference in opinion here.
What if I 'downgrade' to 512mb of Dual Channel 3200, instead of my current 1Gig of 2700 single channel ? I can handle spending $90 on a needless upgrade a lot better than $170.
Is 1Gig a little excessive anyways?
I guess it would depend how you use your machine. Using myself as an example, my main home system is used for some general business apps, surfing, some graphics work and the rare bit of video editing. The dual-vs.single-channel comparisons I've found show I 'might' see a 10% increase. For me, that is hardle worth spending the money on. However, if you run a lot of memory-intensive apps, the faster memory might make more sense. What processor are you running?
As far as the quantity, if you routinely are gobbling up more than 400Meg of RAM during normal useage, then the extra 512 would be very useful. I assume you are running XP, which will happily use all the RAM you throw at it. I believe (don't quote me) that Win2000 stops seeing any benefit at 768meg.