I have 2 computers and one has an older version of electrum that I actually got phished on and lost coins.
OK, so the main wallet is still safe. Good. Before acting at all, you should start by checking if the coins weren't already moved away by the hacker.
In the main wallet do 2 things:
0. This is a safety measure. If you didn't do this, please copy the seed of the main (newer) wallet onto a piece of paper.
1. Open it as usual, get an address (receive tab, new address)
2. In this wallet do File->New/Restore, name it like OLD BAD WALLET so you know not to use it normally
3. From the old computer - it doesn't matter it doesn't connect - get the seed (bottom-right, there's a seed button) and use it for restoring on the new computer [continue what you started at step 2]
4. From this restored old bad wallet send the funds to the address from step 1 and you're done. (Always double check addresses when sending).
If at starting Electrum you get into this "old bad wallet", don't worry, use File->Recently Open and get the other wallet (possibly default_wallet). And if it doesn't work, you still have your seed so you should be fine.