Question about memory upgrade and motherboard ASUS

[CodeVisio]

Hi,

I've an old asus motherboard, A8N-VM with two modules of DDR 400 (512mb each one).
I gave look at around and it seems some modules of DDR of 1gb each are available.
Can I add a DDR 400 (1gb) module to the motherboard directly?
That is, can I have installed at the same time the two modules of 512mb and the 1gb one?
Or do I have to thrown away the two moduels and install the 1gb only?

Thank you

 

[mubin]

You can use 1gb with your existing 2x512mb memory. Your mobo support max 4gb. Just make sure that they are at same speed(400)