I use Firefox on Modern Buisness Platforms due to the features.[P4 2.0Ghz+,512Mb Memory+] However on Gaming Rigs and older machines i use K-Meleon due to low memory usage which is suitable for watching Youtube Videos on older pre P4 platforms, Online Java and Flash Games that are memory eaters and overall fast browsing.[Its faster than IE5.5 but w/o the bugs, the constent freezes/BSOD Errors, Is a Modern Browser that supports CSS and e-mail clients and has tabbed browsing.]
[I mainly use windows so using a Windows Only Browser is OK for me.]