if you're using win xp then 1GB of RAM is still fine. if you're using vista or seven you're going to need at least 2GB of RAM. but i think it is better to have 2GB of RAM if you have gaming in mind even with win xp. if you want to take full advantage of 5570 you're going to need better cpu than your current one but i think it is hard to upgrade considering how old your platform are.
Thanks, do you have any suggestions because all i have is pentium 4. Would a Intel Xeon work? If not please give me some suggestions. ALSO all im gonna do is play Minecraft, which isnt some sort of top notch game.