For information purposes the manual for the HP C762NR states: "Supports up to 2GB"
HP G7000 Notebook PC and Compaq Presario C700 Notebook PC Maintenance and Service Guide, p2 (url:
http://h10032.www1.hp.com/ctg/Manual/c01301275.pdf)
I wonder if the motherboard is in some way limited to addressing 32bits of address space. While 2^32 = 4294967296, i.e. 4G, the motherboard will still need to address various pieces of hardware as well as the memory, and as such may not have sufficient resources to support the 4GB of memory and the other hardware at the same time. Since a lot of manufacturers recommend pairing memory modules you would have 2x1GB=2GB and then 2x2GB=4GB. Thus since 4GB is not supported, 2GB must be the maximum that they support.
Interestingly,
2GB maximum RAM limit - Notebooks suggests that some other combination could be possible for some laptops. I guess you might get 2.5GB, maybe even 3GB into the laptop.
Anybody else got any thoughts?