That's  what I did with my first PC.  I had an XT
and a PC, and I
 thought the PC was dead because it wasn't booting like the XT.  Then I
 left in on while messing around with the XT, and all of a sudden it
 booted.  I felt much better, knowing that the second half of my new
 acquisition booted too, even if it did take longer :-) 
No, it isn't that.  I remember before when I first turned it on there would be a
flashing cursor in the upper left corner of the screen.  Now there isn't even that.  I
waited several minutes and there were no beeps or disk activity, either.  And I know the
monitor works because I tested it on another computer.
  I sold the PC on Ebay after I was tired of it.  
Yeah, I'm the guy that bought it :-)  This is your old PC.  BTW, a friend of mine was
able to get me another monitor for it.
I'll try messing with it a little more this afternoon.  Thanks to everyone for the
suggestions.