Inspiron 1525 memory (RAM) & Graphics Upgrade

Hi I bought a Inspiron 1525 laptop with 1GB of Ram & Intel Graphics Card & now I want to upgrade the RAM & graphics card. I play games, watch movies & use my laptop a lot & sometimes when I look at Performance in Task Manager I see "Free 0" for Physical Memory; But I don't know which Graphics Card to choose between:

1. ATI Radeon HD 4890 - http://ati.amd.com/products/radeonhd4800/overview-4890.html

2. Nvidia GeForce GTX275 - http://www.nvidia.com/object/product_geforce_gtx_275_us.html

3. ATI Radeon HD 4870 - http://ati.amd.com/products/Radeonhd4800/index.html

Which I can I install on my Inspiron 1525? Are they compatible with my laptop?

What about my RAM? I need to upgrade it to 3 GB. Is it possible? What RAM do I buy? :emotion-7: