Now tell your friend that the doc he sent you had the macro virus in it and that he should do something about it. And NEVER say "Enable Macros" unless you really, really, REALLY know what the macro does and you really, really, REALLY trust whoever you got the doc/xls/etc. from.
We very recently had a long discussion about viruses and Macs. There are no active MacOS viruses in the wild that anyone knows of. BUT any MS Office installation can be hurt or at least stopped by a macro virus, so pay attention to anything you didn't personally create.
Damn virus writers!