In theory you'd be correct. But some motherboards, even when they're not operating under the constraints of 32 bit addressing, can't handle more than a certain amount of memory. In my case, my laptop's motherboard can only handle a maximum of 8GB.

This is a fairly common problem: http://superuser.com/questions/308310/what-limits-a-motherbo...

1. The memory controller will impose its own limit, which may be less than you'd think.

2. The form factor may also impose a limit. You won't find a DDR stick larger than 1GB, for example.

Of course, if either of those were the cause of a 2GB limit, then you could make the case that the whole system should be upgraded, but that's a lot more expensive than a couple of sticks of RAM.