hi and welcome. win 7 can run on very few resources. In order for us to help you we need more information about it. Could you take a snip of the task manager in the processes tab. It woud help to know what FF is using how much ram is avvail, how big the page file is, etc
I have the Asus Eee PC 900 running only 900 Mhz 1GB RAM 4GB+16GB SSD
I installed 7229 and very happy with the performance...have to shrink the 7229 and install on the 16GB SSD and cloned on the 4 GB SSD cos the 4GB SSD is the faster drive.