My SSL Certificate has expired

Friends,
I recently walked into a job as s sysadmin at a small no-profit. We use Exchange 2003 sp2 with OWA. The SSL certificate has expired and I want to create a new one. I’ve never done it before but after reading the instructions, it doesn’t seem that hard to do.

My question is is there a way to do this in a test environment (i.e. just my machine first and once I get it working, go live with the new certificate)?

Thanks in advance for your help

Kevin