rflemin

I've got so many problems, so many dead ends, that I don't know how to define it.
I bought a used G1 and successfully jailbroke it to work on AT&T. All went well, if slowly, for about a year.
I don't remember how I did the jailbreak, but I don't think I bought a code. Then last week, every time I turned it on, it showed the splash screens, but then the screen would go blank. I did a factory reset, but stall out when I try to synch with Google. I keep getting the message that I do not have a network connection and that there may be something wrong with my SIM card. I got a new SIM card from AT&T but still get the same message. I get up to three bars, so I do have a network connection, but perhaps not a valid one because the phone still thinks it is on T-mobile but I don't have a valid account with them.
So I tried installng a new ROM. I downloaded Dreaimg.nbh, copied it to a new SDHC card, swapped that for the existing card, and hit Camera and Power. I get the color bars, and sometimes the menu. But when I select Install, nothing happens - no progress bar, no message, no nothing.
To further complicate things, my Win7 laptop can see the phone with Device Manager, even claims to have downloaed and successfully instaqlled the HTC Dream driver, but Windows Explorer can't see it. I think there is a setting that will enable mass storage on the phone, but if I can't get past the Google sign-in, I can't access any of teh settings.
If I can't solve this soon, I think I will just buy a Motorola Braval, dump At&t and get a no-contract carrier.
Thanks for any help.