Will I gain much in performance by upgrading RAM in my Dell Optiplex GX280 small desktop from 2 GB (2x 1GB DIMMs) to 3 GB (3x 1GB DIMMs)? I understand the 32-bit OS will not recognize >3GB so that's why I'm not shooting for 4GB (the physical maximum of this machine). The machne runs Win7 32-bit Home Premium OS and is rather slow. The alternative is to jump to a new machine, probably a i5 processor laptop (trying to delay that expense, if practical). Thanks much.
I would just go for the 4GB so you can run dual channel on both sets of DIMMs. This will result it faster bandwidth over three sticks of RAM. However just dropping an extra GB or two of RAM into a machine isn't going to make it significantly faster. It will definitely help some though.