How do I move the certificate and key from IIS5 to Apache?

Start the certificates mmc for the web server and select 'All Tasks', 'Export' against the site certificate. Do not choose to export the CA certificates. Specify a password. Specify a filename (e.g. mypkcs12.pfx). Copy the resulting .pfx file to your Apache web server.

Then import the private key and cert file into Apache using the following commands:

openssl pkcs12 -in mypkcs12.pfx -out pfxoutput.txt

You'll need to enter the password at least once.

Load pfxoutput.txt into a text editor and save each certificate as a separate file.
Also save the private key as a separate file (e.g. myencrypted.key).

The private key will probably be encrypted at the moment. i.e. looking something like.....

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,.........
.........
-----END RSA PRIVATE KEY-----

If the version of Apache we're using doesn't allow encrypted private keys, to decrypt the private key run the following command:

openssl rsa -in myencrypted.key -out my.key