I prefer Vista x64 to the other versions of Windows. There were a couple of quirks to get used to, but overall, it's a distinct improvement over XP. There are still driver issues with some printers, but as long as you don't have that problem, go with Vista x64 as your OS.
If you don't like Office 2007, there's always OpenOffice, which is almost identical to the older Office. There are a couple of quirks with it - it throws more quote-marks into CSV files than Excel does, which may create an issue if you aren't expecting it. And I like the way Excel pops up the little gliph that lets you change items after you paste, to "Values Only" or "Formatting Only", etc. With Open Office's Calc program, you have to do "Paste Special..." and then check/uncheck the things you want to paste, which is not as nice.
Other than that, I generally don't notice much difference between OpenOffice and Office.