Blue Sweeper, The linux kernel is on a lot of things but not the Linux that we are talking about here..........
The question was, if Windoze is so bad, why isn't Linux on everything. My answer was, it is in one form or another, for which you gave an example of as the Andriod phone. If the question was rephrased to why is Linux or UNIX not on all PC's, then my answer would have been quite different.
MicroSuck and to a certain extent Intel, have a huge stranglehold on the PC hardware market. If it weren't for the likes of MicroSuck and their policy of buying out all competitors, we would have MUCH better PC's with MUCH better operating systems.
Vista was a complete bundle of shite, which Windoze 7 has put right. XP, with the correct service patches applied was very stable. Trouble is the registry just kept growing and growing so the PC got slower and slower. I regularly (at least once per year) reformatted the hard drive, re-installed XP and it would run fine for another year.
My 5 year old laptop has Linux Mint installed, it's very stable, everything works, all the software on it is free and it's every bit as good as my latest PC from work which has Windoze 7 installed. In some respects, personally I prefer to use the old laptop for everyday use on the Internet.
The OP says he has Windoze 7 on his PC. Fine, why change it if he's happy with it. But you could install Linux and dual boot. A small partition of say 10Gb (it will run on a lot less if you want) is all that is required to try it out. If you boot up Linux, you'll find that you can still access all your documents on the Windoze partition.