Many years ago, a wise boss told me it's a nifty idea to be the first to be second - you can learn from the mistakes of the bloke who's too fast off the block.
The other lesson was "always have a path back" - I still have (to this day) the install disks for my Office 2003: this is the third or fourth PC they've been installed on. The updates take a while these days, and the .docX .xlsX and .pptX converters are needed, but I still copy over my "settings" file with things the way I like them.
I still have my two Win 7 install DVDs (I thought I needed two - one for the desktop, one for the laptop). When Win 7 goes, unless there's something as good on offer from MS, I suspect I'll be joining my techie pals round here and using Linux.