Re: Linux...4) No rebooting, no virus menace, fast, robust systems. Low TCO.
@Eadon - If you weren't so pedantic about other OSes it would be fair to not be pedantic here.
Anyway, a Modern Windows server only needs to be rebooted rarely, updates aside.
The thing is that with any OS on micro or mini computers, if you need big uptime, which isn't affected by hardware problems or reboots, you'll cluster it, at which point it doesn't really matter if you need to reboot every so-often. You certainly wouldn't update your software on a live system, when you can remove a cluster node, update and re-introduce the node.