The best OS on x86 is definantly Windows 2000. Under each question is a ranking of Win2k, Linux, and Be.
1)Does it have excellent hardware support?
Win2k-Yes
Linux-Supports some hardware, people making lots of drivers
BeOS-No
2)How stable is it?
Linux-Extremely stable to moderately stable depending on quality of user
Win2k-Not as stable as Linux tweaked perfectly but more stable then almost anything else.
BeOS - Stable, but not to the level of Win2k or Linux. Definantly still a strong point of the OS
3)Does it have excellent software support?
Win2k - Yes
Linux- Yes but no (Lots of develpoing tools, little stuff for entertainment, and we are talking about an all around package
BeOS - Absolutely horrid
4)How easy is it to use?
Win2k - Arguably the easiest here
BeOS - Macs should have been like this
Linux - Anyone who thinks linux is easier then Windows has been using linux too long =)
5)How fast is it?
All 3 OSes are very fast, but Be wins the crown here. I don't want to call Win2k or Linux for #2
6)How well do they scale?
Linux is the best at scaling, allowing room for a tiny little network to a massive worldwide powerhouse.
Windows 2000 scales very well to large systems, but not as well as Linux
Be was intended as a desktop OS, not a server OS.
7)How ubitiquous is the OS
Win2k is supported almost everywhere, hands down
Linux is quickly growing and might overtake Windows someday, but that day is not today
Be is a dead OS in this regard, almost noone uses it.
8) How good is the OS for a desktop? (Single user overall capabilites)
Win2k wins it here, for the whole package deal. It isn't the fastest (But it is fast), it isn't the most reliable(But it is reliable), it is arguably the easiest to use, it is what most people are used to so you don't need to retrain. It just works.
BeOS comes in second. While it dosen't have MS Office or even staroffice, it has equivalent programs (That are much less bloated but nearly as functional I might add) but they aren't compatiable with Office. It is also easy to use, and it flies. Problems are lack of hardware and software support and lack of networking.
Linux comes in dead last as desktop OS because it is so hard to use. It has an MS Office equivalent program that is compatiable, but it is very hard for most people to use. Take your average secretary in front of a Linux box even with Eazel running and they will be confused and having no idea what they are doing. Try it and see

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So Linux gets the #2 spot, and Be takes #3.
I am only considering those 3 OSes because if you want something that is