Tomcat-
yep, the ol BSOD..pretty irritating little surprise when it jumps out from seemingly nowhere..anyway, it can be just about anything and sometimes you get lucky and can figure it out right away and sometimes even microsoft tech dont have a clue. That stop error may (or may not) help you figure it out. If you can get online with another computer you can go to microsoft.com and do a search for that stop error code, if its something that pretty common you will get an explanation article which usually has a fix or at least will give you an indication of what could be causing it..again, if you're lucky this will at least give you an idea of where the problem could be or at the very best be exactly what the problem is in your case and a step by step on how to fix it.
If that approach is not possible or unsuccessful, then the only thing you can do is try to figure it out yourself... usually its something you did the last time you were using the machine...you installed something or added some new hardware or something was changed/added without your knowledge and its not playing nice with your windows installation. If you remember what it was you added or changed then great, as long as you can get windows started in "safe mode" usually by pressing F8 during startup - you can go in and remove whatever it was and restart.
If you can't remember or did not change anything, then it gets a little more sticky..and it could be just about anything...some driver got corrupted, some program is missing something and hanging, etc, etc. Things get more complicated from here and usually involve a systematic process of elimination to find the culprit. There are "cookbook" articles on "how to recover from the blue screen of death" online that explain in detail what to do and how to narrow down the possible culprits untill you figure it out - sometimes a real p.i.t.a. but otherwise its the old bring it in for service an pay through the butt.
Good luck and hey, its a challenge, right.. who's gonna win you or that stupid machine??!