Cable VS. DSL Proxy results

Ok so I am currently running cable and am a semi-noob when it comes to ISPs, Proxies, and router/NAT firewall. I'm currently running cable internet and am wondering if while using a software proxy (Tor+Vidalia+Privoxy) how well am I anon. Does my IP become re-assigned before it hits my ISP or after.

Is there anyway to say change my IP before it even hits my ISP going outbound??

Hello!