In Bitcoin-qt:
1. Click 'help' -> 'debug window' -> 'console' tab
2. If you wallet is encrypted, unlock it by typing walletpassphrase "your wallet password" 600
3. Type 'dumpwallet privatekeys.txt ' without the single-quotes.
Wallet keys will then be dumped to privatekeys.txt in readable format.
Create a new wallet in Electrum, and use sweep function to sweep the private keys.
Thats the solution to your problem. But if you have stored 'larger' amounts of BTC on this old wallet you may be more cautious when doing this on your everyday-pc.
There is always the risk of malware waiting to grab private keys out of the ram/clipboard and stealing funds.
The safer way would be to
(initially make a backup of your wallet.dat) use a bootable linux disk to do the dump/import of your priv keys.
Either with the core (linux-)wallet or pywallet. There are quite a few tutorials available online.
And to awnser your initial question: It doesn't matter whether you copy/paste your file or 'drag' it into another location.