help - laptop ram upgrade

[heX]

I am going to upgrade my lenovo z61m laptop from 1gb to 4gb of ram. I have no idea what I am looking at.

For example what is the difference between

http://www.newegg.com/Product/Produc...82E16820148234

and

http://www.newegg.com/Product/Produc...82E16820148087

I don't even know if this is the right ram. I think I am supposed to be using PC2 5700 667, but for all I know I can be using something else. I really have no idea here, ram has always confused me. Can you guys help me out here? I have looking to upgrade for about 60 bucks including shipping. What would be the best bang for my buck?

edit:
Found this-
http://www.crucial.com/store/listpar...0Z61m%20Series

I still don't know what the fastest set up would be for me. I have Vista 32bit so apparently I only get use out of 3gb-3.5gb. Is there any other way to utilize more than this with 32 bit, or do i need to do a reinstall?

If you can answer any of this or just 1 part, please reply and help me out. Thanks.