I've heard that US credit/ATM cards without an embedded chip might not work in some (primarily unattended automatic) paystations in France.
I thought I'd found a way around this for until US banks start adding chips. Despite the horrible conversion rate, I converted some money at Travelex before leaving the US, getting part cash and part on a chipped, Euro-denominated, Travelex "Cash Passport" MasterCard.
Turns out to have been a waste of effort. The only place the Cash Passport worked where one of my stripe-only US ATM or credit cards would not have worked was in the Paris Metro (where it would have been simple enough to use cash anyhow). The automated gas stations and some toll booths that did not accept my regular credit card refused the Cash Passport as well. Most other toll booths, parking garages, etc. (and of course all merchants and restaurants) were fine with my US cards. And my banks' conversion rates, even after adding their fees, were still at least 10% better than Travelex's. The only plus here is that without any additional fees, Travelex allowed me to convert what was left in cash and on the card back to dollars at an almost reasonable rate (though I still lost what they took in the original conversion).
And don't think the Travelex card is a good way to use cash machines! Use it only for purchases -- you'll be charged extra if you take cash from it at an ATM. Again, your bank card is a better way to get cash. My Bank of America card worked at BNP Paribas machines with no extra ATM fee.
I'd be interested in whether anyone knows why the chipped Travelex card failed at the automated gas station and at toll booths southwest of Paris. (My US cards worked at toll booths to the northwest. And no card worked at one parking garage in Rouen.)
One theory: The stored value on the card was not great enough for a gas station? The machine accepted my PIN but refused to proceed with the purchase. There was, in fact, less than €100 on the card at the time, although my gas purchase in the end was less than what was on the card.
Another theory: The toll machines do not have ATM keypads. So do they only accept "credit" cards that don't need a PIN and not ATM cards that do need one?
(Cross-posted as new topic from original discussion "Chip and PIN credit card" at http://www.tripadvisor.com/ShowTopic-g187147-i14-k4190894-l32681029-Chip_and_PIN_credit_card-Paris_Ile_de_France.html)