Keeping track of the CPU/ram from the Menu Bar (or other suggestions)

Hi everyone.

I would like to add Activity Monitor on the Menu Bar, if that's possible, so I can keep track of my memory and CPU usage. The preference in View > Dock Icon isn't working for me because I have to choose only one. Plus, Dock icons are very small, due to it having many apps on it.

Another solution to my problem would be an app, or whatever, that could somehow warn me when an app is taking up too much ram or CPU. For example, while browsing and I visit a website that uses, say, above 50% of CPU, a notification can pop up to warn me, I close this website's tab and thus avoid having the fans run faster.

I could use a third party monitor software like iStat etc. but I don't really trust myself with it. I think I'd mess up my computer, besides Apple suggests not to install such apps. Correct me if I am wrong.

I am currently using Snow Leopard on a MacBook 4,1.

Thank you very much for your time. I am open to any advice.