I'm no expert in such things, but I think the Cirrus & Maestro things you are on about are ATM networks rather than credit card networks. I think it just means you can use your card in another banks ATM with no probs. All my (US bank issued) mastercard and visa cards have the cirrus logo on them.
malc4d I'm surprised that a US retailer would take your card. When my folks back home buy stuff from US sites and have it sent to me (in NY) they've had no isuues. Sounds a bit strange that a US company doesn't want to take your money......
Gareth.