Click on the Calendar tab to show the calendar. Select View-Calendar-Calendar Pane Make sure Show Calendar Pane and Calendar List are checked. Select the calendar in the list you want to be the default. The calendar that is selected will be the one that is the default when adding and event.

I just tried this but by deselecting the holidays calendar (and selecting only the "home" calendar), the holidays disappear off the calendar display - what do I need to do to "keep" both calendars functional, but making the home calendar the default for new task entries?

Nowhere did I say Deselect a calendar.

There is a difference between selecting, clicking on the calendar so it is highlighted, and deselecting as in removing the check mark.

right -- okay you meant click on the (already checked) calendar to "select" it -- got it; could have done without the sarcastic tone, though

OK I will ignore your questions in the future if you are that fragile.