Project 64 does D3D now, which is very good. It is heavily CPU dependant; the video card is only good for rendering the graphics. I'm using a Tbird 1.0 and it emulates at full speed. Since I've got a GTS-V card, I can even run it at 1280x960 4x FSAA without taking a speed hit 🙂
My current box has 384mb ram, which I feel is plenty for running lotsa stuff. BTW, try holding down Win+ E for a few seconds to launch 50 or so explorer windows (only do this with WinXP so that you can kill them all at once). All those Explorer windows only use ~50mb of ram 🙂