I'm thinking of upgrading from MX7 to 8, since I can download the developer's version from adobe's site. My question is: Will it at all affect my website? I mean, my web server supports CF8 (and MX7 of course)... will I need to change any of the code on my website? If so, I don't think it'd be a good idea.
ColdFusion 8 is 100% backwards compatible. In addition to the new features, the performance enhancements (particularly in object instantiation) are huge. I am quite involved in the ColdFusion community and manage a ColdFusion User Group. PM me if you run across any issues you can't solve.