Best Operatiing Systerm for Computers/Laptops?
If you need good UI and most of softwares available for that OS, then I would recommend Windows XP SP3 x86/ Windows XP SP2 x64 (don\'t go for vista, vista is too louzy) or wait for Windows 7 to get released.
If you want to get better development features and robust then I would recommend RHEL 5.3 (Red Hat Enterprise Linux).
Apple Mac is also a good OS, but you have to use most of proprietary softwares from Apple.
It is always advisable to go for x64 versions of OS now a days than x86 version of OS.