Welcome to the SysInfoTools forums.
First, you are doing the correct thing by working in odt files - they are designed for use with Writer and Writer is designed for use with them.
Converting to a .doc file will always cause problems. It is much better to use the Word 97/200/XP doc file as it is the latest.
Formatting differences may be because .doc treats some of the elements in your document differently or does not support them. You can optimise Writer to work better with Word (Do you want a return after a table for example). Word 98 is very old!
A common problem is using a font which the other application does not have or does not support. Remember that the name of the font shown in the Writer font box is not necessarily the font being used - it is the font the document is calling for. If that font is not available, the Operating System (or AOO) will substitute a different font.
So, your solutions are:
1 If you can use a PDF, then File > Export to PDF > create a PDF.
2 If you must use a .doc, then File > Save as > choose Word 97/200/XP doc, and reformat it yourself.
If you would like to upload an example file with a page or two showing the problem, someone can look at it. If the file has confidential material in it, you can obscure the contents by changing every alphabetic character to an " x ", and every digit to an " n " with
Find and Replace - Tick Regular expressions (under More ...)
Find box [:alpha:]
Replace box x
Find box [:digit:]
Replace box n
The limit here is 128kB, or use a fileshare site like mediafire for larger files.
I hope this will helps u..