give open office a go before you decide to purchase something.
especially if your a switcher it helps. it runs in x11 which might be a bit slow but its free and can open any type of format you throw at it.
give it a go before you decide to throw $399 or $199 for ms office.
you never know you might like it.
i like it cos it looks familiar to windows programmes with the file etc on the top of a window, as well as its free. the only prob is that its not yet mac osx native so no aqua or other stuff. but openoffice are worling on this and should be out soon (thats what they say anyway)