(this will get fancier soon, but for now here is the important stuff)...

So, your windows machine is running slowly?  Takes forever to boot?
Only usable for about 5 minutes after each boot before the thing slows
to a crawl, so bad your mouse does not even track smoothly?

Here are the likely problems and possible solutions.  They work better
with XP, as it is a much more "durable" operating system.  But they
will work to some degree with Win98 or WinMe as well.

What has happened is that you probably have both a trojan / virus, and
a collection of "slimeware" applications that have snuck on your
system.  Trojans / virii exploit stupid design decisions when windows
was built to install software on your system to do bad things (like
attack other peoples systems).  Slimware sneaks onto your system
through the front door "Click here to speed up your internet
connection", or "get todays weather" but does much more then it admits
to doing.  Slimeware and trojans are also easy to pick up using tools
for the theft of copyrighted material (like MP3's).

Once you have the trojan / whatever, your system is exposed, so anyone
could have done anything.  So the right thing to do is reformat the
drive and reinstall from scratch.  This could easily end up eating up
a weekend though, so if you want to take a chance and be done in an
evening, try the following.

0) (works better under XP then Me)... bring up the task manager
   (ctrl-alt-delete) and kill anything and everything.  When in doubt,
   kill it.  This should speed up your system long enouogh to do the
   rest of the steps here.

1) Use the control-panel add/remove software utility to remove
   everything you don't recognize, and everything you don't need.  Be
   brutal.  When in doubt, delete.  You can always reinstall it if it
   turns out you can't live without it after all.  

2) Download and run the tool AddAware (www.lavasoft.de).  Make sure
   you get the latest updates for it before your first scan, then
   follow the instructions to run it.  It is really easy. Have it
   delete everything it finds.

3) Update / enable / get latest definitions for your virus software.
   Run a full system scan.  Your trojans may have broken your scanner,
   so reinstalling might not hurt.  Though updates have traditionally
   done the trick for me.

4) Clean up any viruii / trojans found.  If the antivirus tool won't
   do it, do a google search.  Most popular virii have fix utilities
   out and available (from reputable sources).

5) Repeatedly run windows update (off the control panel window, or
   start button) until it tells you no more updates available.

Once you have done all these things, the system will probably be
running MUCH better.  Repeat process every couple months to keep
system running well.  And friends don't let friends run a windows
system connected to the internet without a firewall, so get and
install a copy of zone alarm (decent free version) if you don't have a
hardware appliance / router (which is faster, better, and much less
grief to live with).

Good Luck!
Bill Kilgallon  (Bill at KilgallonFamily dot com)