In your experience, what is the most accepted credit card overseas, Visa or MasterCard?

I think in general VISA just wins but really, both are accepted in most places. AMEX less so.

Be careful in France when using a credit card. The French are quite switched on electronically but there banking laws are a bit peculiar. It is illegal for anyone to go overdrawn in France so credit cards are not a cultural thing, rather they use VISA (Carte Blue, pronounced carrta blur) as a debit card straight from their bank accounts. To really confuse matters, when you present your card, they often give you a small keyboard like a calculator to punch in your personal code. This has led me to interesting conversations in supermarkets when I have tried to convince them that I don't need one. Sometimes it works but sometimes it doesn't. VISA international say that they should accept foreign cards without the code but if you are outside of the main cities on a Saturday afternoon and they don't believe you, then you will go hungry and have no cash until Monday (it has happened to me!).

Interestingly of the major European countries, in Germany only about 20% of the population have a credit card so their use may be limited outside of major cities.

The UK has a credit culture almost as developed as the US and you can use them almost anywhere. There are a couple of major store groups which have resisted accepting them until this year but now they do so penetration is now pretty much complete.

In Ireland you should be ok in most major towns.

Holland, Belgium and Luxembourg and the Nordic countries, I'm not so sure about but there should be no major problems in major towns.

Australia, no worries cobber, unless you are out in the bush but as there is nothing to spend your money on anyway, it isn't a problem.

Finally, check with your bank that you have the correct card for automatic teller machines. Most countries will accept cards from banks in other counties which is very useful in countries where the banks only open for a few hours a day and in any case, the exchange rate is often better than in a hotel.