Thank you Dean,
I'm using OS Leopard (but thinking of upgrading to Snow Leopard).
Intel Core 2 Duo
150 GB HD
40 GB HD free
Nvidia GeForce 8600M GT 256 VRAM
It's not so much about the render (at this stage, because I'm newbie). What happens is that my computer got really slow when I tried to criate some particle effects in Maya, and wasn't responsive to other tasks (which is to be expected really).
This happens as well with other sotware: when I'm using Gimp to edit photographs (my work for now)...
It's not a big deal really, at least for now, since I'm still an amateur with 3D.
I just thought it could be good to upgrade now that I want to get into it, and was indecisive about these two options.
But I think I'll follow your 4GB advice (my inclination from the star as well).
Thanks again Dean,
T