is double encryption on a Win7 file a bad idea?

I am running Windows 7 Professional x64 on a personal, not work, laptop.

I have encrypted a file using Explorer's encrypt attribute from the properties dialog.

Before I put this file to a cloud storage system like Dropbox, I wanted to also
use something like TrueCrypt on the file.

Would it be a mistake to have a file encrypted by both Win7 and TrueCrypt encryption?
I want to be as sure as possible that this file is protected from any possible hacker attack
on Dropbox.

Thanks in advance for your opinions and help.

Tom

Not sure it would be good idea to use 2 separate. All you can do is experiment. Do it and place the file up and wait 1 day and see if you can decrypt it.

I save all my important stuff off to a password protected usb jump drive and I won't plug it in if I think anything funny going on.

Thank you for the reply Veegertx. I'll use another encryption app on top of Windows encryption and see how that works out.