money change for Cambodia?

Hi,
we are at the moment in Chiang Mai, Thailand and we want to go to Cambodia. I think that I don't have enough US dollar in cash with me so I need some advise. I do have Euro's and Thai Bat enough, so what to do? Change euro or thai bat in Thailand into US dollar or should I change money in Cambodia? Looking foreward to replies (and sorry for my not so fluently English)
ad ontskul, Chian Mai.

Change your cash in Cambodia they accept Thai baht + €,s

Also in Phnom pen, you can withdraw $US from ATM's, but for Laos and Cambodia leave, having spent all your reals or Kip, or else you will be papering the walls with them.

You can change Euros and Baht into dollar in all major towns in Cambodia.