The hard drive on my computer died, and I was wondering weather or not it is possible to install the same copy of windows on my next hdd. I read somewhere that you can not reuse a OEM copy if your compyter dies, but I'm not sure if that is true.

Yes and No

Yes you can legally replace the faulty internal HardDrive
No you cannot legally replace the whole computer, and use the same OEM key

Windows Vista OEM allows you to reactivate Windows up to and including 10 hardware changes in the computer, but you must activate through phone support after the installation has finished, takes about 10 minutes. However as kimsland said you cannot legally replace the whole computer and continue to use the same OEM key, though I am sure alot of people would take this approach.
cheers
Hynesy

Thanks. I was worried that I would have to spend another 130 bucks fixing my computer.

Though I am sure Microsoft would love for you to spend more money.