Originally Posted by berry120
Partially true. 64 bit vista (or anything) can use practically as much RAM as you throw at it as long as it has a 64 bit processor (which it needs to run anyway.) 32 bit address spaces however are limited to around 4GB (2^32), in practice this shows up as less in vista, usually a bit over 3GB. That's the general rule anyway.
The limit isn't to do with the fact it's a quad core or anything like that, it's all in the number of bits.
This much is true. But you must remember that Vista's kernel is a resource hog, most other OS's will be able to hold any amount of RAM if they have a fast enough processor.