Word of advice: do not try the DIY approach. Reason: screws. I attempted replacing scratched touchscreen myself and ended up paying ca 50 euros extra for the repair. Why? The tiny screws did not come out but instead broke down! The technician told that they are supposed to be replaced on every repair. I have succesfully repaired e.g. motherboards and other stuff but N900 was a total failure.
FYI, I am also one of those who snapped the screws when replacing the LCD. I took out 5 of them without problem but failed at the last one....
I eventually sent my phone to palco for repair. They have good price and repaired the device super fast (less than 1 day). But my replacement LCD now have bright spots, and they peeled off my screen protector for no reason. The former issue I would not blame them, it seems to occur on some N900 as well and might be a pressure point issue. The later I am not happy with, I feel there are a couple new scratches, though I cannot say for sure.