Booting from drive on another Mac

Hi all,
I am just wondering if changes made (ie. files deleted, moved, etc.) made on a drive that I've booted from will still hold once it is put back into the original MacBook Pro? So I guess a bit of detail regarding the situation would help. I have a unibody MBP, and apparently the nVidia card was a dud as it kept freezing sporadically this past week, and then just wouldn't turn on.

So I cloned the hard-drive with SuperDuper before the screen wouldn't turn on, luckily, because I saw that coming. Now before I took my MBP in for repairs, I had to remove some files, passwords etc from the MBP's hard-drive. So I plugged it into my Mac Mini and booted from that drive. The Mini had an older version of Mac OSX on it, but it still let me boot from it, regardless. Now, I am a web developer by trade and I have a lot of sensitive information about upcoming campaigns, etc., that if leaked, I can get into a lot of legal trouble, so I made sure to "Secure Empty" that information from the original drive.

My question is, will the changes I made to the Hard-disked booted from on the Mac Mini hold when it is placed back into the original MacBook Pro?

MBP has OSX 10.6.7
Mini had OSX 10.4.*

Thanks guys,
-G.

Yes, it doesn't matter what computer deletes or moves the files on a Harddrive, they remain deleted and moved.

It would make my life a lot easier if they didn't (sometimes) ;-)

Well that's certainly reassuring! Thanks, Kaveman! Something occoured to me though. I'm wondering how they will even log-in to my account without my username or password. I'm sure they have ways to circumvent that, surely? Or do they generally just swap with their own HDD when they do Logic board replacements?

Generally, If we don't have the User Name and Password we don't bother trying to go there. Yes you can either Reset the Password, but you would know if they did that. Or pop the whole drive out of the Mac, put it into an external enclosure, do some tweaks and then access it that way.

As you can see a lot of work. That of course doesn't give access to anything that been deleted.