Vista on new HD problems, laptop

Hi, I'm not an expert; I rely on forum threads for everything I need to learn, but I can't find help for this specific problem. I'm actually hitting a wall on 2 different projects and have posted here on the other one too.

My niece, who loves to download crap and doesn't heed my warnings, gave me her dead HP Pavilion dv6000. After research, I replaced the HD with a compatible one, then used a Vista* ISO disk I created. It booted and started loading, then froze at the "loading files" stage. I made a 2nd ISO disk, same result. I put the unit away for several months and just started again.

I ran the HD and RAM tests from the BIOS and they passed. I ran memtest and it froze after about 20 hours at 84% with no errors.
I tried a UBCD disk, and now it just starts with a black screen or a splash screen but no response to F10 or anything else, no matter which boot disk I try. Sometimes it does nothing for awhile, then emits a loud, high-pitched beep that goes on until I shut it down.

I don't give up easily but there are obviously gaps in my knowledge and I'm going crazy. Can anyone guide me to a solution?

Here are the only specs I can find without going inside the laptop:
http://h10025.www1.hp.com/ewfrf/wc/documentdocname=c014...

Thanks,
Auntie Doreen

*(I don't like Vista but wanted to keep it simple and put the same OS it had- I have the product key, and I can't afford a new OS anyway)