Gaz - multi-threading is a function of the operating system aka windows XP vs. windows 3.1 so your old system is as capable as your new one in that regard... You will see a performance increase with the faster processor, faster FSB and DDR memory and 1gb should be quite sufficient and you can always add more later. If you use rendercow and set up your old machine and your new machine to render a scene you should see a pretty good decrease in render time for animations (almost half). For still images it doesn't matter because rendercow sends a full frame at a time so for a single frame it either renders on your main computer or the old one... anyway - throwing extra computer(s) on a render even if they are older systems (like p2 etc) will really help improve your render time