Mine came yesterday, can't believe how quick it is compared to my old iMac G5 2.1GHz!! Everything is sooo much snappier, the only downer I've noticed it the hard drive seems to be louder, but that could be just because the fans are so damn quiet on this C2D iMac!
Overall I've very happy. I opted for the 20" with a 2.33GHz C2D and the 256Mb Vram upgrade, I also got a Wireless Keyboard and Mighty Mouse because I thought the wires in my last iMac spoilt the look a bit, made it cluttered!
You have the exact set up that I am interested in. Looks sweet. I thought I wanted the wireless keyboard and mouse for the same sort of reasons you mentioned, but I'm just not sure. May go wired first, and maybe switch to wireless later. Still saving money up, so I have plenty of time to change my mind over and over again. Anyway, enjoy your new toy.
One quick question on the wireless KB & mouse. My computer desk has a shelf for the keyboard and mouse that slides under the desktop so it is a few inches below the desktop. Is that likely to be a problem? Don't know if the keyboard and mouse need line of sight to the monitor or not.
The Keyboard and Mouse both work for me when I'm sitting on my bed and that's about 3 meters away from the iMac so I don't think them being on a different level on your cabinet will have any effect. Also, you'll save quite a bit getting the wireless pack as a build to order option.