For Word:
As mentioned by another user, you can open your Word 2003 Documents (.doc)
and Templates (.dot) in Word 97, Word 2000, and Word XP (2002) without doing
any extra work. The only problem you'll run into is that some features found
only in Word 2003 might not display correctly, work the same way, or show at
all in Word 97, Word 2000, and Word XP (2002).
Here are some helpful articles:
Strategies for sharing documents with different versions of Word
http://office.microsoft.com/en-us/assistance/HP051902821033.aspx
Turn on or off features introduced in recent versions of Word
http://office.microsoft.com/en-us/assistance/HP052489031033.aspx
For Excel:
As mentioned by another user, you can open your Excel 2003 Worksheets
(.xls), Charts (.xlc) and Templates (.xlt) in Excel 97, Excel 2000, and
Excel XP (2002) without doing any extra work. The only problem you'll run
into is that some features found only in Excel 2003 might not display
correctly, work the same way, or show at all in Excel 97, Excel 2000, and
Excel XP (2002).
I don't know how much this will help regarding Excel, but it was all I could
find that was related:
Using Excel 2003 with earlier versions of Excel
http://office.microsoft.com/en-us/assistance/HP051985111033.aspx
For PowerPoint:
As mentioned by another user, you can open your PowerPoint 2003
Presentations (.ppt), Slide Shows (.pps) and Templates (.pot) in PowerPoint
97, PowerPoint 2000, and PowerPoint XP (2002) without doing any extra work.
The only problem you'll run into is that some features found only in
PowerPoint 2003 might not display correctly, work the same way, or show at
all in PowerPoint 97, PowerPoint 2000, and PowerPoint XP (2002).
Features affected by working with a PowerPoint presentation in an earlier
version
http://office.microsoft.com/en-us/assistance/HP052619821033.aspx
Bottom line:
The Word/Excel/PowerPoint 2003 file format is the same format in
Word/Excel/PowerPoint 97, 2000, and XP. Only the features used by
Word/Excel/PowerPoint 2003 in the file are different or not available in
Word/Excel/PowerPoint 97, 2000, and XP.