Okay, first things first, read through that xdaforums link I posted (I know there are a lot of pages, and if I had the time to do it I'd flip through them and find the links you need myself, I'm just slammed with final papers I have to finish right now). What you need to find in that thread are the details of how to get it booted into recovery or developer mode (normally some button you need to hold down while you boot it up), and you also need to find the stock 1.6 image (though it appears there are 2.1 images out there, I saw at least one link in that thread).
Bottom line, you're going to need to get the stock image onto your sd card, probably in a file called update.zip, and then get the tablet into recovery mode (it sounds like it's booting past that mode right now, which likely means that whatever ROM you tried to install is either corrupt or simply doesn't work on that device), and then push whatever sequence of keys are required to get it to load the file on your sd card into the tablet. It's different for every device, but I suspect that process is documented in that thread somewhere.
The good thing is that you *haven't* broken it, you just need to reload the OS.