I tried opening my wallet.dat file without having qt client running, but when I browse the files to open it with the qt client it doesnt add it to the list of programs to use.
you can't open bitcoin wallets as a file. you must place it in bitcoin-qt's data directory.
For the OS-specific file location to "restore" your wallet backup, see:
https://en.bitcoin.it/wiki/Securing_your_walletHint:
%appdata%\BitcoinIf Bitcoin doesn't have a wallet.dat in it's data directory when it starts, it will create a new blank one.