IBM just announced a free office suite, IBM Lotus Symphony, that will directly compete with Microsoft Office. Available to anyone for free, it consists of a word processing app (Lotus Symphony Documents), presentation app (Lotus Symphony Presentations) and spreadsheet app (Lotus Symphony Spreadsheets).
Should you take a look at this? It's worth a look, since it's free for business and personal use. One good thing about it is that it supports the Open Document Format (ODF) standard. Since this is an open standard, anyone can create a program that interacts with ODF documents. What does this mean? This means that you can take documents created from Lotus Symphony and choose another program to edit your documents (example: OpenOffice, which is also free).
The IBM Lotus Symphony site also states that it supports Microsoft Office formats, although I don't think that includes the latest 2007 formats. Another caveat is that certain advanced features like macros are not supported. Encrypted Microsoft Office documents are also not supported with Lotus Symphony.
If you're convinced or curious, download IBM Lotus Symphony at the link below. You'll need to register (free) with IBM though. Another thing is that when I visited the page it states that the version is beta 1 and the only language listed is English. That shouldn't be a problem though since you're reading this. :)
Edit: Since someone came here looking for a mac version, I think you should be aware that IBM Lotus Symphony is for Windows XP and Linux only. No OSX or Windows Vista versions are listed at the download page at this time.
Edit2: If you don't want to register with IBM, try one of the login/password combinations at BugMeNot.
IBM Lotus Symphony seems to quite popular as their site is being hammered right now and access is fairly slow as compared to earlier in the day. If I find an alternate download link, I'll update this post.
Edit3: In related news, DownloadSquad has a quick peek at the recently announced Google Presentation. OpenOffice was also updated to 2.3.0.
[Link: Download IBM Lotus Symphony]
[Source: Official IBM Lotus Symphony statement]