Some programs require .net to work. Of course you can uninstall it and if one or more of your installed programs don't work you can reinstall it.
BTW, .net doesn't use any RAM to speak of. It works in conjunction with other programs.
Is it possible to Uninstall Net.Framework from a home PC? I have XP Pro, but I noticed that this uses a lot of memory ( I have 1 Gb), and I would like to get rid of it if it isn't essential.