To the best of my knowledge, all units purchase from Bob will be the same, unhacked. The TigerDirect machines, MAY have a different bios, and might allow the installation of any harddrive, but this is doubtful.
Yes, they should be able to be hacked. We know that units very similar to this exist in Spain modified to run XP. We have the necessary replacement bios, so we just have to figure out how to re-flash the existing bios. This should wipe out the loader that is running, that checks for the harddrive / OS.
I have to admit, there was a large part of me that thought it would be easy as taking out the old HD, and putting in a different one. That would have been too easy, and we've learned that some, not all Internet Appliance makers went out of their way to lock down their machines to prevent people like us from re-purposing their hardware easily.
I'd recommend you read the rest of the thread to get an understanding of our current situation. Even if you're not a big Linux guy like me, there's something that I'm sure you can contribute in the process.