Computer turns on, monitor shows "No Signal"

My computer runs on Windows XP and is a desktop PC from emachines.
When I power up my computer and turn my monitor on the computer starts running and so does the monitor, but the monitor stays on the “No Signal” screen until it finally goes to black. Which is what it does when nothing is getting sent to the monitor.
No beeps are coming from my computer, but I still reseated the RAM stick that is in it, several times. None of those times its worked. Ive tried powering it up without the RAM stick, put it in the second slot, none of this makes any difference in what happens when powering on the computer. It does not beep and always loads up.
Another thing I done was try to reset the CMOS. I took the battery out, as one site said I should do, and try to power it up with the power not on (but the light will come on momentarily thinking there is power) which it did. The site said that will reset the CMOS, I have no idea if it did because it still wont send to the monitor. I read another site which instructed me to remove the battery and wait about twenty minutes before the memory resets then try to start it, that didn't work. I moved a plastic hat kind of thing that was covering two of the pegs in the CMOS area, moved those pegs to the top and middle instead of the bottom and middle, booted, nothing happened. I removed the thing completely too and that did nothing different.
Another thing I done was remove the hard drive (to hopefully get some of the information off of it) and put it into another computer which resulted in, for whatever reason, the computer asking me to authorize the copy of windows with microsoft for whatever reason. The copy came with the computer, the computer came from Future Shop so I didn't figure on something like that happened. So I put it back in the right computer and let it be.
Another thing I did was try a different monitor in it, which gave the same results as before.
Now, after doing
That's about all I could find out to do, I'm not sure if Ive done them right or what and I'm starting to figure, obviously, that the video card section of the mother board is ruined and maybe I need a new video card... or... god forbid... I need a new mother board.
I was really wondering if any of you might be able to tell me anything else I could do, anything I have done that was done wrong, or that it is the mother board or video card section of it. If it is the video card section of it that is ruined can I get a separate video card? Or would that mean the mother board is ruined no matter what.
Another thing I was worry about was by messing around with the hard drive in the second computer, did I ruin or erase any of the information on it? Is the hard drive still salvageable?
Another, possibly curtail, piece of information is that before this happened I blew a fuse in the house and the computer was on that fuse. That shut the computer down and it hasn't worked since. I figure since it wasn't a surge (or what I think a surge is, which is the power flicking on and off) it wouldn't bother anything. But as I've found out with this particular computer, anything seems to be possible.
Thank you for your help, and I apologize this message is SO long, its my first time posting on a help site and I thought it would be best if you got as much information about what is happening with me as possible.

When the computer powers up, it powers up pretty much as it normally would. The fans run, even the CD drive opens and closes. As far as when it beeps, that isnt happening this time. Ive found that anytime it beeps and dosnt show up on the monitor, that has been a problem with the RAM. For me at least, in the past. So I just take the stick out, put it back in and it works fine. But it dosnt beep at all this time. Weather the RAM stick is in the computer or not it dosnt beep. I can figure that on what you said at the end of the message that the motherboard is ruined. I was worried about that but wasnt sure, I thought I might be able to get off with just putting a video card in it instead of using the video card that is already on the mother board.
Thank you a lot for your help.