It's hard to tell since the specs aren't as detailed for the rendition.. I would just get the cheaper/available stick and add that to your 1gb for now, see how it runs before you go and decide to replace the 1gb stick with another to brand match or something. There is no way to make a 32-bit OS use more than 3gb of ram as far as I am aware.. the 32-bit just isn't capable to utilizing any more than that.
Brand name does and doesn't matter just like in most cases.. Crucial has been good.. OCZ, kingston, etc.
Hop in, strap down, and hold on tight.