OK, 10.4.11 Tiger is now a tick over 5 years old. Have you considered an upgrade?
Unless there is an Apple guru around who can shed more light on the subject, I do not think Safari 5 is compatible with Tiger. I am of the understanding that 4.1.3 is the latest Safari release you can use. And it is now old enough that I question how well it can render today's page coding.
You can give
Mozilla's Firefox a test-drive, but I think Firefox 3.6.28 is the latest release that Tiger can use there. Firefox is releasing a new stable upgrade every 6 weeks, so release numbers are growing by leaps and bounds, with Firefox 17 being the latest release. With Apple's upgrade strategies, I really think it's time for you to look into upgrading OS X.
I never could get into the entire OS X lifestyle, but I still use my mid-2007 iMac on a daily basis. I'm using it to type this message, as a matter of fact. I upgraded it from Leopard to Snow Leopard and then decided it was time to turn it into a Linux machine.