People who have bought these devices and loaded up the v1.7.4 firmware update (or custom firmware based on it) will know that the Android Market doesn't really work. (v1.7.2 didn't have the Android Market at all)

Problem: You can do anything you like - including buying paid apps....but the Market won't actually let you download anything. Ever. 

There was a work-around that saw you, the user, going through multiple steps, wiping app data, killing the Market app and signing in fresh.....just to have ONE briefly / partially successful download session.

The underlying issue is that these tablets don't have a SIM. So they aren't assigned a unique "androidID". For the market to work properly, you need to have a valid androidID in (on the device):

/data/data/com.google.android.googleapps/databases/accounts.db

It's an SQL database. 

A clever person at Slatedroid has worked out what the problem was and how to make it work. The instructions are here

I've followed these instructions and they work. My Market now works perfectly, 100%. 

If anyone needs any help with this, let me know and I'll see what we can do. 

But the problem is fixable. It took me about an hour to go through it and work it all out....and if I had to do it again, it would take me about 10-15 mins.