Yet another Call to Undefined Function help request

Hi all,

PLEASE, don't just toss the e-mail... I think I have a unique enough situation to warrant this e-mail.

First, I have searched the mailing lists for the answer to my problem.  I have also tried to find the answer through the documentation, but have been 
unsuccessful.  Mailing lists are always my last resort.

Here's the situation.  I have an *old* Cobalt Raq appliance with Apache 1.3.20 and an older version of mysql on it.  I have a customer that wants to 
use a database on his website, and rather than update this old, unsupported appliance and possibly break something, or go through the hassle of moving 
this customer with 100+ e-mail addresses to a different server, we have installed a new, dedicated mysql server to use system-wide for any of our 
customers, and ourselves, to use as a db server.  This seemed like a good idea at the time, and I think it will work well once we figure out the bugs 
here.

Now, everything was going swimmingly, until we tried to access the db with php on a web page (which is where we got the call to undefined function). 
It was an old version of php, so I thought I'd upgrade, not as scary as upgrading all three pieces of software.  No resolution there.  I compiled it 
with mysql support, but still get the undefined function error.  Now, on the new db server, phpinfo reports a whole section on mysql.  On this older 
server, there is no mysql section in phpinfo.  I can log in and access the databases remotly from the Cobalt server using command line mysql; I would 
like to try this at cli using php but don't know how.

I am obviously missing something and I can't find the answer anywhere, other than "reinstall apache, mysql, and php", which is kind of scary on a 
server this old that is running as well as it is.  Not only that, but my ego is kicking in here and I would really like to understand what the problem 
is rather than just reinstalling everything... That just seems too M$ to me.

Any suggestions?

Thanks,

Alex