And if you have a legit hosting, why not just contact technical support, and have them fix that? Or you breached some rules of that company's hosting? All in all, if they detect you are using a proxy, they WILL find you, it's only a matter of time, and they WILL contact your ISP, with all the details, and that ISP may choose to stop providing any services to you... And somepne may even press charges against you...
What you described when using RapidShare, is called NAT... Name Address Translation... Many ISP's choose this option, to minimize IP address usage... Certain numebr of users is hidden behind a certain type of router, maybe even a proxy of a sort, and all users behind it, have the same PUBLIC IP address... But again, that IP CAN be traced back to your PRIVATE IP address...
When we sum all that up, you can't successfully hide your IP, due to a fact that it MUST be known to in order for you to receive packets... I wouldn't suggest you trying to fool the system...


