How to Optimize for rendering

I have a scene for the Blender Cookie Contest but i can’t render it. I didn’t work so much with Blender and i think i don’t do the things the best way they can be. I have a lot of textures, and probably this is the problem but i want to use them. If there is no other way i will make it without them, but i really want to use them.
When i render it via GPU, it has only 1280MB memory, and it went out of memory. If i try to render it via CPU it’s too slow. I have to render it with 2000 samples and i couldn’t do it. I can make only one render and to delete the rest, but i want to make renders from different angles. When i try to use particles for the grass outside or for the carpet it crashes.
Is there a way to see the size of all textures used in the file for example?
My system is:
Windows 7
Video Nvidia GTX 570
CPU Q6600

Here is the file:
Thanks a lot in advance.