Defragging the registry is one strange idea. While it made a difference in 1998 and prior, why folk do this must be those snake oil sales folk trying to trick folk again and again. Restore from backups and well, if you want to do dangerous things, no one will stop you.
Bob
After updating all XP files Apr 8, I defragged complete Then ran a registry defrag
power outage crashed my system after defrag but before restart.
F8 does not access safe mode, or other commands.
can reach repair at C;\windows but can only access limited command functions typing. such as copy, mbr,fdisk, mbr, etc...
ran chkdsk /p, but no other commands. can not change dir or run a command such as rstrui
this is second PC, can use other pc for access to files from internet, for downloading, etc... but that system is Vista.
Thanks in advance I realize this is a big one. Prompt Replies.
I have been using this 2nd system for all major backups,as well.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic