Here are a few tips that I have adopted for my own use after a few years of falling on my face... I'll just go down my Explorer set of folders and point out what worked/works for me.
1. Under My Documents...since most often, every time you want to save something you end up defaulting to this folder, and then have to go searching for the "real" place you want to save something...I have put a bunch of short cuts in this folder leading to my favourite save sites
2. I keep all my internet settings on a text file in this folder...to include IP addresses, all the fora that I visit with code keys, all my Software titles with code keys/serials/etc.
3. Under c:\
...!Kill Box for those stubborn files that my KILLBOX.exe prog sends its refuse to
...NTBACKUP Folder, using the MSXP-NT backup tool included with XP-SP2...to back up sysfiles etc., Docs/Settings, etc.
...BACKUPS-Reg Folder, with copies of the registry backups...I only keep about 3-4
...DOWNLOADS
...DRIVER BACKUPS
...HAUNTED HOUSE...now this is an interesting one...I discovered sometime ago that those files that refuse to be deleted from a certain folder, have no problem taking up residence in another folder...so I just drag and drop...then I set up my Internet Browser to use the same folder as a cache...so when the cache is cleaned out...the stubborn file goes with it !!!
...INTERNET...to keep my browsers in, and all addons associated with their use...plugins and the like
...LIBRARY...this is where I keep copies, in separate TOPIC folders, of every problem I have encountered along with solutions and the bit o' software that I discovered would deal with it, if available...including fora suggestions if they work...
...MISSING FILES... every time an error message tells me that a file is missing or corrupt...I set out to find it on the internet and then save an extra copy in this file with an explanation of its path and the issue related to it
...MS-DOS...just in case Microsoft sees the wisdom of bringing sanity back to the computer I keep the most updated version
...NEAT CRAP OFF THE NET...all images that I have stumbled on the have moved me in some way, and which get encorporated into various projects
...PRODUCT RECOVERY KEY...speaks for itself
...SAFEMODE...a collection of repair utilities that work in SafeMode...
...SYSCLEAN...my PC-cillin saving grace...runs in cmd window or SafeMode
...TROJAN WARRIORS...various anti-Trojan related files...no matter what, they always seem to squeak in...expecially the Vundo
...WEB...all web related activity...blogs, personal web site, etc.
AND THERE MAY BE MORE THAT YOU CAN THINK UP
Keep your system well organized and logical. Windows likes a neat and tidy work space. Windows also likes to put things where IT wants things to go...so go with the flo!
SLAVE DRIVE: instead of risking stuff on a partitions that may get affected, and is pretty much immune to any interference
...backups of all 3rd party ware, along with keys, serials, codes, etc.
...one ready to go copy of those progs I need immediately when there is trouble...for example "Registry First Aid" and "Windoctor"
...one copy of the latest reg back up and backup of Docs/Sets
BURNED CDs: additional off-site backups of everything: if it's that important, the only copy of it should not be on your computer
I wrap that all up behind one fire wall, six anti-malware programs and one anti-virus program
VIRTUAL DRIVE...one copy of the original i386 Folder and contents from my XP-SP1 setup and install OEM disk
ONE SET OF MS FLOPPIE DISK INSTALL DISKETTES: NOT FOR VISTA
Without Service Pack 1
Download details: Windows XP Home Edition Utility: Setup Disks for Floppy Boot Install
With Service Pack 1
Download details: Windows XP Home Edition with Service Pack 1 Utility: Setup Disks for Floppy Boot Install 
