Virtually all Win7 machines from the big manufacturers come with a copy of Office 2010 preisntalled. This can be used in three ways: as a trial, or it can be upgraded by puchasing a licence for one of the full versions, or it can be activated as an "Office Lite" version for free - this give cut down version of Word and Excel, but good enough for most home users
As for your copy of Office 2007, this will install OK on Win7, though for the sake of stopping confusion I would suggest you uninstall the Office 2010 trial first
If you are one of those who didn't get an Office setup disk, just the product key, you can download the Office 2007 installers from Digital River. This page links to them
Direct Download Links for Microsoft Office 2007 Suites and Applications « My Digital Life
These are real genuine downloads from Microsoft's online reseller. They are not warez or hacks
if any of these don't work, post there are alternatives from Digital River. Also the full set of Windows Vista and 7 are also available from them. Not however XP or 2003