Regarding the memory upgrade, first we would need to find a contractor willing to take it on. Then, we have to consider the reaction we'll get if we tell Mk.1 owners that it will cost them 200 quid plus shipping for an extra 4Mb of RAM! Some of you will understand the issues and go for it, but others will be very vocal in their displeasure.
I'm not sure the extra memory will be all that useful anyway - it'll give longer caching times between disk spin-ups but the main use for it on the Mk.1 is the voice recognition software, which definitely won't be available at an upgrade for older players.
Rob