Depends on what you're doing. If you're okay with very limited Web use, even 2GB is viable (or was about a year ago when I retired that machine). More normal levels of Web use, you're going to need more RAM. Not sure about GPU-constrained loads like 3D modeling, as I never tried them on that machine. But other than those and some games, nothing on Linux should require even 8GB. Server systems can make do with even less.