Mac OS X 10.4.11 2011

If it does the job for you, then there is no need to. Many PPC Mac users still use Tiger. The price of Leopard is astronomical at the moment since it's not officially available anymore.

If it still works, why upgrade?
And you are not the only person still suing Tiger, there are even people using lower versions, even non X versions of Mac OS.

But if you thing upgrading to Leopard would improve things and it is worth the money (129 USD), then go for it. It introduced QuickLook and Spaces and Time Machine, maybe they are very valuable functions for you.

no need to spend all that money for leopard , give the cash a good purpose and add some more ram instead of throwing it unnecessary out of the window for a scratched used leopard retaildisc , tiger still flies especially on a PowerMac g5

10.5.x and higher is also still supported... 10.4.11 doesnt get the updates or support anymore from apple so surfing the internet with 10.4.11 will become more and more limited as time progresses.

What are those things in the seconds pic, Dashboard items? Lots of things taking several MBs each

yes dashboard items definitive ,if you dont want dashboard you can disable it, spotlight is taking its fair share too and can be disabled too

but if you keep activity monitor open you will find that your Mac can handle that , so nothing that should concern you

ok a dual 2.7 great Mac ,but watch inside regular for leaks something that should concern you more then the ram usage of each app or widget , but could you be specific about why you are so concerned , ok 2 gb ram is not a huge amount , but usually more then sufficient for tiger to run smooth , and you will always spot activity when the Mac is on, i mean there is nothing unusual happening in your activities

Tiger is a good os. I'm still running it in a dual boot with Leopard on my G4's. Pretty solid and quick os for it's age.