1. you can install Office 2000 and Office XP without re-installing Windows XP..
2. Partition Magic will be ok as well
3. Win Fax you will need version 10.5 for XP
4. Act 2000 Don't know
5. Norton 2003 is good and will not cause any conflicts
Do it slowly, reboot after each installation then if any issues appear you will know which program has caused it.. Good luck