Questions about memory

[Christer Wickman]

Hello Everybody

I was wondering over if one put in more memory in ones computer does one 
need to change system from 32-bits to 64-bits or can one countinue to 
use 32-bits. I have plans to change memory on my station computer from 
2Gb to 4Gb and even change the speed on them from 667MHz to 800MHz since 
my motherboard which is a ASUS P5KPL-AM can use either 667MHz memory or 
800MHz memory. And one more thing the GPU that on the board is not use. 
I have a graphic-card which is also an ASUS. Which uses G210 GPU on it. 
Which also means that it sometimes borrrow memory from the motherboard. 
I am not sure that this function is use in KUbuntu. There is one more 
thing I have three Linux-system on the computer. The first one is 
KUbuntu v. 14.04LTS, the second one is Elementary OS v. 0.2 the last one 
is Linux Mint 16. The CPU that the computer has is a Intel Core2Duo 
2.20GHz. So does one has to change all the systems one has on ones 
computer? And if so can one do it without installning the system again? 
I hope you can help me with this.

Yours
Christer Wickman