OT: European Cell Phone Service, Looking for coverage in London, Paris and Amsterdam Options

[Part Pricer]

I know this is off topic. But, I'm sure that this group has some knowledge & experience in this area, so I'm looking for some advice. I've googled this subject and I'm more confused than ever. So, I decided to ask the experts. (IMG:style_emoticons/default/smile.gif)

I'm heading over to Europe in the fall and I'm going to need local cell phone coverage. This will only be for calls being received and placed to phones in the countries where I will be visiting. I will not need to receive or place calls to the U.S. from this phone.

I will be spending some time in London, Paris and Amsterdam (and surrounding areas) and would like to have coverage in all places using the same phone number. I'm thinking that it may be best to just purchase a SIM card that will provide me a number and roaming to all three countries. Which brings me to two questions.

First, I have a Nokia 6230 phone which is unlocked. This would allow me to put any SIM into the phone. The phone is GSM 850/1800/1900 MHz. Will this work? Or, do I have to go with a phone that operates at 900 MHz as well?

Second, who should I purchase a SIM and coverage from? There are so many places that come up when searching for coverage that it's making my head spin.

Thanks