I’ve recently migrated my 2003 DC’s CA to a non-dc 2008r2 server. Everything went surprisingly well. It’s pretty easy. Folow MS’s directions which are basically, backup the CA Database from the MMC, backup the registry. Remove the CA. Install the CA. Restore the database. Fiddle around a bit.
The only issue I had is the CRL. THe old crl was at http://oldca and removing the CA role removes this website. Although the CRL is in AD, it won’t get updated by the new CA. I found this fantastic article which helped immensely with sorting out the CRL. The http one won’t work, but the AD one is good enough (I hope). Just a few points on the article that I didn’t notice, its ldap:/// not ldap:// (three / ) so make sure you type it correctly! I think the whole path is case sensitive too. If “publish crl” is greyed out after you’ve entered the information, you’ve typed something wrong.