I have found Open Office to be a satisfactory replacement, it downloads quickly and is absolutely free.
You can always download it online or get a CD with the program. I have Word 2007 for Vista and it's just great.
I'll toss my hat in the OpenOffice ring. I love it. Abiword works well too if you don't need the spreadsheet, presentation and database. http://www.abisource.com/ There is also Jarte if you prefer something less bulky. It's like wordpad only with formatting and spellcheck. http://www.jarte.com/
I'm with the open-office lot too. Woo! It's useful to note if you're considering it that you can save documents as .docs so they're completely compatible with word and other computers and your documents can be exported as PDFs which is always useful!