Shoutbox

This sounds more towards a product limitation on behalf of your CD rewriter manufacturer...
(Evidence; Windows Reads it as 702mb, firmware updates don't solve it)...
Therefore a few things come to mind;
1) Contact your CD Rewriter Manufacturer, tell them the exact problem, how Windows and Nero recognise it as a 702mb disk, you've enabled overburn, and that you've updated the drivers...be careful to include your exact CD Rewriter model
2) Make sure the disks aren't mislabelled, or you've got a dodgy 800mb disk...
3) Make sure the firmware update worked...