First off, I'm not great with computers.  Here's my problem: I thought it would be a great idea to download windows vista from limewire.  Turns out it was just a trial version that is now over and asking me to activate it.  I no longer have a running operating system and can only access the internet.  I need to find a way to get my XP back, which I think is still somewhere in there trying to get out!  I FOUND a way to get to my files by right clicking on a picture and clicking on "go to my pictures".  How can i get rid of this stupid vista trial and back to my xp???  Please help me.  I"m pretty desperate.This is sort of a gray area because what you tried to do is illegal, but you didn't succeeded and you are INSTEAD left with a useless OS.  So, with that in mind, I will at the very least, POINT you in the right direction...

http://support.microsoft.com/kb/933170

More similar results here...
http://www.google.com/search?hl=en&q=uninstall+vista+revert+to+xp


If necessary, you can try giving Microsoft a call (1-800-MICROSOFT in the US) and explain your situation and perhaps they can give you a hand.  Of course, you may want to exclude the part about trying to download their software illegally.  However, they may very well figure it out anyway.  But hey, it's worth a SHOT.  And just so you know, even if you had succeeded in getting a full version of Vista, you would still most likely encounter SERIOUS problems because illegal OS downloads are 95% worthless.  'Tis best to stay away from them altogether and upgrade the legal way.