OK, be gentle... new user with questions

Hello List! Undoubtably this topic has come up repeatedly. We have an NT4 / IIS server coming on Friday. We are building a site for a county gov't from scratch and have decided to use PHP as our scripting language. Most of the county databases use Oracle, so we are excited not to have to use ODBC. Oracle is running on NT servers, the entire county is running on NT servers (so please don't tell me how much better off we'd be with a UNIX server... I know already, but these decisions were made before I came here). My question is: Is PHP4 stable enough to start with? Should we use 3 and its extensive documentation to get our feet with, or should be just jump right in to 4 and pray? Thanks in advance, John