Switching to a different Office file format is always painful. You probably won't want to jump head first into the XML file formats that come with Office 2007, but it does have big advantages.
For one thing the files take up less room because they're all automatically "zipped" to save space - see Figure 1. Instead of a binary file that dumps what's in your computer's memory to a file and sorts it out later, a ZIP file is made up of all the elements in the document. Even if one aspect gets corrupted, you'll be able to recover the rest of the document. If you're in a hurry and need to cut down a picture-heavy file to send by e-mail, you can take a copy, rename it with the .zip extension, open the file in Explorer and delete the image files.
When Office 2007 is finished, you'll be able to switch to the new formats when using current versions of Office. But for now, you can get smaller files in the existing formats by following a few simple rules. Start by checking what's set under Tools-Options-Save.
Turn off "Allow fast saves". Hard drives aren't slow enough for it to make things noticeably quicker, and it means you get bigger files that are more prone to problems. Instead of deleting what you ask it to get rid of, Word just crosses it out to remove later. This will happen only if you then save the document as a new file.
Enable "Always create backup copy" - see Figure 2. That way if you change your mind after you've hit Save, which clears all the Undo steps, you at least have an earlier version to go back to. Office 2007 doesn't include Fast Save. It lets you Undo even after saving a file.
Finally, always pick the most recent file format available. PowerPoint 95 files are much larger than PowerPoint 97, for example.
Adjust image size
Don't keep larger images than you need. Your digital camera or scanner will create high-res files but, unless you're printing them at full size, you don't need this resolution.
If you're looking at a document on screen, saving for the Web or viewing PowerPoint on a projector, more than a 100dpi (dots per inch) scan is wasted space. And if you crop an image in Word or PowerPoint, lose the extra pixels by choosing View-Toolbars-Picture and clicking the Compress Pictures button.
Choose "All pictures in document", select Web/Screen or Print under "Change resolution" and tick both "Compress Pictures" and "Delete cropped areas of pictures". If you embed a chart from Excel in another document, you get the Excel file with it, so you can go back and change the underlying data.
If you're sure you've finished working on a spreadsheet, you could embed an image of the chart instead. <Alt>-<PrintScreen> will take a screen grab of the current window, or a tool such as ClipMate (www.clipmate.com or on the Cover Disc of the November 2006 issue of PC World Magazine) lets you take a picture of a specific object.