Unfortunately, the Satellite A65 doesn't have the option of going to 2 gigs of ram. It has 256MB of nonremovable memory and then only one slot to add memory to, which has a maximum size of 1GB. So, you are maxed on ram already. Checked with Crucial, Corsair, and OCZ memory configurators and they all say the same thing.
Which CS4 are you wanting to install? According to Adobe, Photoshop CS4 requires 512MB with 1GB recommended.
http://www.adobe.com/products/photos...op/systemreqs/