In answer to rednova's question, I'd keep your A2000. My personal opinion is that should you want a more capable machine then you already have plenty of upgrade options available for your A2000. You can add upgrades to it as and when you want/can afford them. It is capable of going beyond the A1200, except maybe for Quake.
Gaming wise I think the best games are all OCS/ECS anyway. I don't even have an A2000, but I've always wanted one. Like you I have little room in the house.