can i run linux as an operating system without Microsoft o/s on the HDD
YES … or with Windows.
will i be able to transfer my MS office files ie word exel over to Linux from my external HDD that i use for backup and be usable
YES … LibreOffice can read and write Microsoft office docs … caveat, if they’re in .docx format there may be some slight formatting changes (pics moved slightly, font changes etc.) … why not download LibreOffice for Windows first, and see how well it opens the Microsoft Office docs.
will my photos be accessable on linux os
Absolutely 
i have all my music store as wma will this play on linux ?
Hmm … if it contains DRM, I can’t say for sure … but Linux allows you to boot from a CD or USB stick to a fully working desktop without changing what’s on your hard drive at all … so Why not create a LiveCD/LiveUSB and test drive it on your current system ?
Google chrome ?
Yup
Norton 360
Nope … but then you don’t need anti-virus for Linux
← seriously
what cant i do with linux
Besides run Windows software, not a lot … but then there are nearly always a Linux alternative, and itr’s usually free.
(can I add that it’s sometimes possible to get Windows software running In WINE [a Windows compatibility layer], but not always, and to differing degrees … I do however hear MS Office 2007 can be made to work … but quite often getting Windows software to work in Linux through WINE is a PITA, so it’s usuallly best/easiest to go with a Linux native alternative)
which linux is best for me as i see there are different versions/types
Ahh, the $64,000 question, and the one that will get you as many different responses as respondents 
My vote goes for PeppermintOS … but then I’m part of the development team … so I would say that.
As I mentioned before, probably best to test drive a few distro’s on LiveCD/LiveUSB and make up your own mind.
Currently, you may find more help/tutorials/etc. available for Ubuntu based distributions such as Ubuntu (obviously), Mint, Peppermint, etc.
[EDIT]
Oh, nearly forgot … welcome to the forum 
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