It won't work, so I'll save you a lot of time and effort here.
Two very fundamental things about Windows are going to be working against you. The first is that Windows is more or less designed to not be bootable from an external device. The second is that it's a device dependent OS, so the hardware profile from the old system will cause all kinds of problems.
Assuming you overcame these two rather large technical problems, you would face a legal issue. The license for the copy of Vista lives and dies with the broken laptop. There are no transfer rights. So, you would, in effect, be pirating that copy of Vista assuming you could overcome the technical issues. It's entirely possible there are other programs installed on that drive which would have similar license restrictions.
So the long and short of it is: It won't work, don't even bother. If you want to use the broken laptop drive as extra storage, that's one thing, but you have at least two mountains of technical issues to surmount, and then a legal one after that. Which means this is all the more assistance you'll be able to get on this particular issue on these forums. Aiding and abetting software piracy is not permitted here.
I took the hard drive out of a broken laptop (had vista OS on it) and hooked it to a newer laptop (has 7 on it) via USB SATA adapter. What I want to do is use my now external hard drive (vista) to boot up on command and be the primary receiver of downloads, cookies, etc. I went to BIOS and found "generic external hd" and told that to boot first, an error message saying can't come out of hybernation popped up. can anyone help me? Thanks
BTW- both OS's are already installed