Simple AV question

The most reliable computer I have ever owned is an IBM running Windows ME. It has not given a hiccup in 10 years.

But the better known AV programs will not run on ME and so I am using ClamWin.

It is rather basic and does not, like the more sophisticated AVs, catch nasties in mid-air before they can enter the computer, so scanning has to be done manually.

The settings include the options of quarantining a virus or deleting the infected file.

Is it OK to leave the infected files in quarantine (it has found a trojan) or should they be deleted totally?