Open Office should be ready by the time you get your dual core Mac. Look at http://www.openoffice.org for details.
Microsoft has an Office for the Mac if you can't do with Open Office.
"will I be purchasing 2 versions of every the software app so that I can work on a file on the mac, but through network, work on the same file on a pc?"
My sony vaio running on xp has come down with a virus that none of the anti-spyware/virus apps can find or eradicate, so when I reformat that pc and give it to my kids to use, I'm thinking of going the iMac dual processor route. I've been using pc-based apps for everything - and all files, devices, and programs (turbo tax, for instance) are formatted for the pc. What happens to those files if I go mac? (stupid question??) Will I have to purchase new drivers for my camera, treo, printer, network, router, external drive, etc? Ditto for programs, so that I can open and use current files (especially work-related files using MS-office)? And since I'll still have pcs in the house, will I be purchasing 2 versions of every the software app so that I can work on a file on the mac, but through network, work on the same file on a pc?