How can I get rid of these settings on my hardrive?

Ok, so in 2007 I bought an Xbox Arcade, which came with a controller and a memory stick(256MB) That was definitely not gonna be enough room for everything. So I purchased a hardrive(20GB) off Amazon, but I made the mistake to buy it from someone who had already used it and put their account info on it. Ever since I have been putting my account and games on it and I play mostly mature games I guess. This person set the limit on the hardrive to T for Teen, movies PG-13, and TV PG-14, which means that I cannot download or watch M rated trailers, demos, or anything above the settings. I have gone to system settings and turned off the Family Settings, and it hasn`t helped in any way. I have also turned Console safety off. If I decided to get the new Xbox Slim and transfer my account and whatever I want to the new hardrive, would I be able to download and watch whatever I want since I won`t have the Amazon hardrive anymore, or will his settings be transfered as well:( If theres a way to keep my account( I don`t wanna have to make a new one and start over again) but change the settings, please let me know cause I feel like I`m being contained, or should I just try getting the new xbox. Thanks