I want to create a Word document on my Mac Pro laptop, but I will give it to my colleagues, who will edit it and use it on Windows. I have to do the same with a PowerPoint document. Does that work without a conversion?
Ii've just purchased office.mac 2011, and office home and student 2010. which file extension should I save my documents for word, excel and power point to be able to go back and both between my pc and my MacBook air?
The default file formats should be fine. If you want to be safe, save it in .doc, .xls, and .ppt format or export to PDF.
It will work without conversion, if both parties (you and your colleague) are using compatible versions of MS Office. By "compatible" I mean that either you both have recent versions, or you both have older versions. If not, you can save the files to work in other versions.
In Office 2007 for Windows (and 2008 for Mac, I believe), the default file extensions for Office documents were changed. For example, a Word document used to have the file extension ".doc", but starting with Office 2007/2008, the default file extension is ".docx". Older versions of Office (2003 and earlier for Windows, 2004 and earlier for Mac) aren't able to read and edit .docx files. There are compatibility plugins that enable the older versions to read newer files, but not everybody has those.
If you are using Office 2008 or later on your Mac, you should first ask your colleagues what version(s) they are using. If it's 2007 or later, you'll have no problems. If it's earlier than that, then you can simply save your documents in earlier formats. This is done in the "Save" dialogue box, by clicking the drop-down menu that allows you to choose what file type you want to use. Select the one that matches the version your colleagues are using, and they'll be able to use and edit the document without any problems.
If you have an older version of Office and your colleagues have a newer version, you don't need to do anything. The newest versions are all backward-compatible, meaning that they can use older formats by default, with no conversion or special saving necessary.