Need help picking out hardware. Desktop pc

Acer Aspire M1610 Desktop/PC:

I need help understanding and picking out hardware for my motherboard.
I have a older motherboard (cant remember the make off hand) the ram in the older motherboard had a 1gb stick so i tried to put it into this M1610 but the sick doesn't fit? so i need to understand what i need for this.

Basically i want this built for light gaming. Nothing hardcore.
my game needs 2gb of ram but if possible id like to have 2 x 2GB sticks 4GB in total.

It has a 256mb Nvidia graphics card IIRC so in the future that will get updated as well.

 

Crucial has memory modules compatible with your computer in up to 4 GB (2 x 2 GB).

 

Thank you.

Am i correct it what im doing? Rather that just installing the 2 that the game states i need, im going for the 4 so i can play it and i wont need to update the ram for a while?

From Crucial:
DDR2 PC2-5300
From eBay:
DDR2-800 pc2 6400

When buying ram how do i know whats compatible with my motherboard slots ? As i said in my first post my old pc's ram wont fit into the M1610 as the gap in the middle of the ram is just off slightly.

The ram from Crucial is 57GBP
The ram from ebay is currently at 1GBP

currently i want the cheaper option as i cant afford the 57

 

Going up to 4GB max isn't exactly incorrect, but if you're running 32 bit Windows, it won't "see" the full 4GB. You'll only have about 3.3 to 3.5 GB available (an inherent fault of the OS).

If you should for some reason need to re-install 32 bit Windows, you'd need to pull the memory module from bank B before re-installing Windows as 32 bit Windows won't re-install with more than 2GB of RAM installed in the computer. You could then re-install the second module.

Ebay's is more than likely used and the 1GBP would be a starting bid. It could go over the 57GBP that Crucial wants for brand new if a bidding war gets going before the item ends.

As far as the notch in the ram module, my modules both have the notches offset like yours so you'll have to be aware of that when you purchase. Take a good look at the pictures of the actual items for sale to make sure the notches are offset.