Most versions of Windows will report from 3 to 3.5GB of RAM. Are you sure you won't complain about that?
My recommendation today is to stop at 2GB.
Need 4GB ram. I am a new computer builder. Can I use G skill 4GB (2 x @Gb) 240-pin DDR2 SDRAM (PC2-6400) Dual channel for 4GB ram in a GIGABYTE GA-965g_DS3 ATX Intel motherboard.