I just wanted to comment on what you had posted. This is my understanding of the situation at hand with the zv6000. There is actually nothing really "wrong" with the machine. Some users are not very happy with HP for "cripling" this machine. The AMD Athlon 64 processor (at least the ones in the zv6000) have a built in memory controller (hence the 939 pin config) which allows it to use dual channel memory accessing for greater performance on the memory side of things.
Some users have noted that the machine IS infact dual channel capable, but is only using a single channel. In order to take advantage of dual channel memory, the two RAM modules must be identical. Users have tried this and still, the machine uses single channel. Many have contacted HP, and HP seems to be messing up bigtime. Many, many different answers have come from HP, all pretty weak.
My assesment of why the machine does not support dual channel memory is because of the graphics card, and its ability to share system RAM. If shared memory is turned on, one of the RAM sticks is used for this, not both, hence the two identical sticks of ram are no longer identical. A new more sofisticated version of the BIOS might fix this, but thus far, there has been no word from HP about this solution.
There is a forum specifically dedicated to this machine: zv6000 forums