Moving to Europe, how to keep using my phone?

I'm moving to Denmark from the US in a few days and I was wondering if I could use the phone I already have as a pre-paid phone over there. I heard that I might be able to get a new SIM card and then just buy minutes at 711 whenever I need them, but I might also have to unlock it first?

My phone is an LG C1500. It runs on 850/1800/1900 MHz frequencies. I got it from Cingular when I made my plan here, it even says Cingular on it.

So will this particular phone work for me? Do I have to unlock it, and if so, how? How will I know which SIM card and what kind of minutes to buy?

P.S. I don't care about calling anyone in the US with this phone, I just want to make local calls in Copenhagen, Denmark.

It'll work, but unless you use a provider that only uses GSM 1800, you won't get optimal coverage. GSM 900 is a more commonly used frequency, especially in rural areas.

Your phone may work well enough... but you might be better served to get a quad-band phone (or at least a GSM 900/1800 phone, and you can use your old phone when you're back in North America.)