DigitalChaos
The trouble with that new DD GPU block, (other than the fact it looks Pig Ugly to me), Is that it sucks up two PCI slots apparently.
Also some were having trouble with the retainers not fitting on some GF3 cards due to a capacitor in the way.
Butcher
I use cellulose clear lacquer (aerosol can), and my method is explained fully in all the block builds on my site, (sig link). Seems to work fine but it will scratch off if you are not careful.