My question has a few parts: I just installed the 32-bit version of xubuntu a couple days ago on a Dell optiplex GX620 with 486 MB SDRAM (i know) and a 3 GHz dual-core processor with 2 MB L2 cache memory.

I plan on adding 2 GB of RAM (this should be easy right?), bringing the specs up to just under 2.5 GB memory. I've heard that some of the advantages of 64-bit computing come with a larger available memory space, starting at 3 GB. Is there any reason to install 64-bit xubuntu? If so, is it possible to upgrade from the 32-bit version I currently have installed without having to reinstall everything else on here? And lastly, as things stand right now with me running the 32-bit system, if I am installing a program that has both 32-bit and 64-bit versions available, does it make a difference which one I install?

Thanks in advance!