Briefly chipping it that the other components of OpenOffice (or Open.Office.org, as I think they officially call themselves now over some IP dispute concerning the OpenOffice name) are decent substitutes to MS Office as well. OpenOffice Calc does what Excel does, OpenOffice Impress does what PowerPoint does, etc.
I can’t vouch for the more advanced high-level functions, but I’m pretty sure that for almost all of the needs of almost all users, OpenOffice software is practically equivalent to their MS Office counterparts.
I tried OpenOffice Calc and thought it was terrible - very slow (that was a surprise - MS Bloatware was much faster) and missing a bunch of features that I use in Excel.
YMMV, depending on what sort of stuff you do in Excel. If your create elaborate models with dozens of sheets and thousands of calculations, look-up functions etc., differences in speed might become noticeable. But if your Excel files are smaller and more modest, then even a difference in speed at a factor of, say for example’s sake, 10 won’t cause too much worry if the difference is between a hundredth of a second and a tenth of a second in refreshing the output.
It’s the death pool spreadsheet. It does do a lot of calculations (although I have improved that recently) and lookups, but the amount of data is not huge - lists of 800 - 900 names. But the difference was dramatic - numbers of seconds difference in response times, not fractions of seconds.
Trying OpenOffice also taught me that one person’s useful function is another person’s bloat. Bloat is all that stuff that you personally do not use.
So I agree with your YMMV assessment. OpenOffice works for some, not for others.
I was using both Excell and Calc for my project spreadsheets (not terribly complicated), and Calc seemed faster - especially opening for those simple books.
I would be cautious about converting complicated spreadsheets from Excell to Calc. Some little difference could result in tragedy in a big spreadsheet.
For most users OpenOffice /LibreOffice provides the same functionality as MS Office.
There is also Google Docs, which has decent functionality for simple docs.
Microsoft Live Office looks to be a free product as well. I have not tried it, but in all honesty, for all the bashing that goes on MS makes a very good product.
The latest version handles .docx just fine - I opened a .docx file in OO just the other day.
OO has also improved tremendously over the past few years. Many complex PPT files that came out a mess a few years ago now look great.
One more bonus - it does a fairly good job with some pdf files. I was able to extract some fairly complex graphs in a pdf file with OO, and then export to PPT format. Some minor editing was needed for the axis labels, but not bad. On the other hand, I’ve also extracted some that looked awful.