1. I had a computer custom built... 11/12/2009
2. Retailer didn't register Windows 7.
3. Various glitches, crashes etc.
4. Registration now expired.
(note: Computer in question not on the net)
5. How do I register from my laptop (for other Computer)?

Get a new Windows 7 product key (http://windows.microsoft.com/en-AU/windows7/Get-a-new-Windows-7-product-key)